Elevated ghrelin predicts food intake during experimental sleep restriction

The Relationship between Sleep, Obesity, and Metabolic Health in Adolescents - a Review

In this literature review, we discuss the importance of adequate sleep and the various effects of suboptimal sleep on weight maintenance and metabolic health specifically for adolescents. Two major contributors to adolescents experiencing decreased sleep duration and quality, and thus increasing the risk for developing metabolic syndrome in adolescence as well as later in adulthood, are increased electronic screen time particularly at night and early school start times. The less time adolescents spend sleeping, the less quality sleep they obtain, and the greater the disruption of endocrine hormone function. As another consequence, adolescents are more prone to making poor food choices, from choosing relatively nutrient-poor foods to consuming excess calories without necessarily increasing their energy expenditure. These choices put adolescents at greater risk for becoming obese throughout their lifespan.

Associations of short sleep duration with appetite-regulating hormones and adipokines: A systematic review and meta-analysis

In the current study, a systematic review and meta-analysis were conducted to summarize and assess whether short sleep duration is associated with appetite-regulating hormones and adipokine levels. Reference databases were searched for studies related to sleep and appetite-regulating hormones and adipokines. Qualitative and quantitative syntheses were conducted to evaluate the relationship between sleep duration and the level of appetite-regulating hormones and adipokines, including leptin, ghrelin, adiponectin, resistin, and orexin. Twenty-one of 3536 studies, covering a total of 2250 participants, met the inclusion criteria. Leptin, ghrelin, and adiponectin were included in the meta-analysis. Ghrelin levels were higher in the short sleep group (standard mean difference [SMD] = 0.14, 95% CI [0.03, 0.25], p = 0.01). Significant differences between the short sleep group and recommended sleep group were also noted in leptin level experimental subgroup studies (SMD = 0.19, 95% CI [0.03, 0.35], p = 0.02) and ghrelin level cross-sectional subgroup studies (SMD = 0.14, 95% CI [0.02, 0.27], p = 0.03). A rise in leptin and ghrelin levels were also observed in sleep deprivation groups (SMD = 0.24, 95% CI [0.10, 0.39], p = 0.001 and SMD = 0.18, 95% CI [0.04, 0.33], p = 0.01, respectively). In conclusion, short sleep duration is associated with an increased ghrelin level, while sleep deprivation had a significant effect on the levels of both leptin and ghrelin.

The influence of sleep health on dietary intake: a systematic review and meta-analysis of intervention studies

BACKGROUND

Poor dietary intake increases disease risk, and poor sleep influences diet. This systematic review and meta-analysis of intervention studies aimed to evaluate the effect of sleep health on dietary intake in adults.

METHODS

Five online databases were used to identify studies published between 1970 and 2019. Included studies were interventions that modified sleep and reported dietary outcomes.

RESULTS

Fifty four full texts were assessed and 24 publications were included. Following risk of bias appraisal, data were narratively summarised and a sub-group of studies (n = 15) was meta-analysed to determine the effect of sleep on dietary intake. One intervention modified sleep timing and 23 modified duration. Sleep duration was partially restricted (≤5.5 h night^-1 ) (n = 16), totally restricted (n = 4), partially and totally restricted (n = 1), and extended (n = 2). Dietary outcomes were energy intake (n = 24), carbohydrate, fat, protein intake (n = 20), single nutrient intake (n = 5), diet quality (n = 1) and food types (n = 1). Meta-analysis indicated partial sleep restriction results in higher energy intake in intervention compared with control [standardised mean difference (SMD) = 0.37; 95% confidence interval (CI) = 0.21-0.52; P < 0.001], with a mean difference of 204 kcal (95% CI = 112-295; P < 0.001) in daily energy intake, and a higher percentage of energy from fat, protein, carbohydrate (fat: SMD = 0.33; 95% CI = 0.16-0.51; P < 0.001; protein: SMD = 0.30, 95% CI = 0.12-0.47, P = 0.001; carbohydrate: SMD = 0.22, 95% CI = 0.04-0.39, P = 0.014).

CONCLUSIONS

Partial sleep restriction with duration of ≤5.5 h day^-1 increases daily energy intake, as well as fat, protein and carbohydrate intake. Further research is needed to determine the relationship between other dimensions of sleep health and dietary intake.

Sleep problems and their association with weight and waist gain - The Brazilian Longitudinal Study of Adult Health (ELSA-Brasil)

OBJECTIVE

To evaluate the association of sleep problems with weight and waist size gain during four years of follow-up.

METHODS

We investigated 13,030 participants (35-74 years) of the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil), a multicentric cohort conducted with civil servants from six academic institutions recruited between 2008 and 2010. Sleep problems were assessed at baseline by the Clinical Interview Schedule - Revised (CIS-R), designed to detect common mental disorders based on somatic, depressive and anxiety symptoms. Weight and waist size were measured at baseline and at follow-up (2012-2014). Large weight and waist size gain were defined as ≥ 90th percentile (≥1.65 kg/year and ≥2.41 cm/year, respectively).

RESULTS

Sleep problems were associated with higher risk of a large weight gain (RR = 1.11; 95% CI 1.01-1.24) and large waist size gain (RR = 1.19; 95% CI 1.07-1.32), adjusted for age, sex, ethnicity, income, educational level, investigation center, smoking, alcohol intake, dietary energy intake, leisure-time physical activity and body mass index (BMI) or waist circumference at baseline. After additional adjustment for common mental disorders the associations became non-significant (RR = 0.99; 95% CI 0.88-1.12; RR = 1.08; 95% CI 0.97-1.22, respectively).

CONCLUSION

Sleep problems are associated with increased risk of developing large weight and waist size gain, but are not independently associated with common mental disorders.

Sleep Restriction With Circadian Disruption Negatively Alter Bone Turnover Markers in Women

PURPOSE

The purpose of this work is to determine whether an uncoupling of bone turnover markers (BTMs) occurs in women exposed to the combination of sleep restriction with circadian disruption (SRCD), as previously reported in men.

METHODS

Four bone biomarkers (N-terminal propeptide of type I procollagen [P1NP] and osteocalcin = bone formation; C-telopeptide [CTX] = bone resorption; sclerostin = bone formation inhibitor) were measured in bihourly samples over 24 hours at baseline and after approximately 3 weeks of sleep restriction (~5.6 hours of sleep/24 hours) with concurrent circadian disruption (SRCD, recurring 28-hour "day" in dim light). Maximum likelihood estimation in a repeated-measures model was used to assess the effects of SRCD and age on bone biomarkers.

RESULTS

Five women were young (22 ± 2.8 years) and four were older (58 ± 1.8 years). Baseline bone biomarker levels did not differ by age (all P ≥ .07). Bone formation markers were lower after SRCD (estimate ± SEE, ΔP1NP = -9.5 ± 2.8 μg/L, P = .01; Δosteocalcin = -2.3 ± 0.9 ng/mL, P = .04). The P1NP decline was greater in young women (ΔP1NP = -12.9 ± 3.7 μg/L, P = .01). After SRCD, CTX was significantly higher in young women (0.182 ± 0.069 ng/mL, P = .04) but did not change in older women.

CONCLUSIONS

These pilot data are similar to previous findings in men and suggest that SRCD negatively altered bone metabolism in women by decreasing markers of bone formation and, in young women, increasing a marker of bone resorption. If sustained, this pattern of BTM uncoupling may lead to bone loss and lower bone mineral density.

Metabolic Factors Determining the Susceptibility to Weight Gain: Current Evidence

PURPOSE OF REVIEW

There is substantial inter-individual variability in body weight change, which is not fully accounted by differences in daily energy intake and physical activity levels. The metabolic responses to short-term perturbations in energy intake can explain part of this variability by quantifying the degree of metabolic "thriftiness" that confers more susceptibility to weight gain and more resistance to weight loss. It is unclear which metabolic factors and pathways determine this human "thrifty" phenotype. This review will investigate and summarize emerging research in the field of energy metabolism and highlight important metabolic mechanisms implicated in body weight regulation in humans.

RECENT FINDINGS

Dysfunctional adipose tissue lipolysis, reduced brown adipose tissue activity, blunted fibroblast growth factor 21 secretion in response to low-protein hypercaloric diets, and impaired sympathetic nervous system activity might constitute important metabolic factors characterizing "thriftiness" and favoring weight gain in humans. The individual propensity to weight gain in the current obesogenic environment could be ascertained by measuring specific metabolic factors which might open up new pathways to prevent and treat human obesity.

High need for recovery from work and sleep problems are associated with workers' unhealthy dietary habits

OBJECTIVE

We aimed to examine the association of recovery from work and sleep with workers' dietary habits.

DESIGN

Cross-sectional study. Need for recovery (NFR) from work was assessed with a validated questionnaire. Sleep was assessed with five questions from the Nordic Sleep Questionnaire and sleep quality question. Dietary habits were estimated using a validated sixteen food groups-containing questionnaire. Ordered logistic regression was used to explore the associations of NFR and sleep with dietary habits adjusted for age, education, marital status, work schedule, working full or part time and occupation.

SETTING

Follow-up visits of type 2 diabetes prevention study cohort in a Finnish airline company.

PARTICIPANTS

The study included 737 men and 605 women.

RESULTS

Poor recovery from work was associated with a higher eating frequency (OR = 1·03, 95 % CI 1·00, 1·06), higher intake of fast food (OR = 1·05, 95 % CI 1·02, 1·08) and sweets (OR = 1·05, 95 % CI 1·02, 1·08) as well as lower intake of vegetables (OR = 0·96, 95 % CI 0·93, 0·98) and fruits (OR = 0·96, 95 % CI 0·93, 0·98) among men. In women, poor recovery from work was associated with higher fast food (OR = 1·06, 95 % CI 1·02, 1·09) and desserts consumption (OR = 1·04, 95 % CI 1·00, 1·07). Among men and women, sleep problems were associated with higher eating frequency (men: OR = 1·04, 95 % CI 1·00, 1·07, women: OR = 1·06, 95 % CI 1·02, 1·11), consumption of fast food (men: OR = 1·07, 95 % CI 1·04, 1·11, women: OR = 1·06, 95 % CI 1·02, 1·10) and sweets (men: OR = 1·05, 95 % CI 1·01, 1·08, women: OR = 1·04, 95 % CI 1·00, 1·08).

CONCLUSIONS

Poor recovery from work and sleep problems were associated with unfavourable dietary habits especially in men.

Impact of sleep deprivation and high-fat feeding on insulin sensitivity and beta cell function in dogs

AIMS/HYPOTHESIS

Insufficient sleep is increasingly recognised as a major risk factor for the development of obesity and diabetes, and short-term sleep loss in clinical studies leads to a reduction in insulin sensitivity. Sleep loss-induced metabolic impairments are clinically relevant, since reductions in insulin sensitivity after sleep loss are comparable to insulin sensitivity differences between healthy individuals and those with impaired glucose tolerance. However, the relative effects of sleep loss vs high-fat feeding in the same individual have not been assessed. In addition, to our knowledge no diurnal (active during the daytime) non-human mammalian model of sleep loss-induced metabolic impairment exists, which limits our ability to study links between sleep and metabolism.

METHODS

This study examined the effects of one night of total sleep deprivation on insulin sensitivity and beta cell function, as assessed by an IVGTT, before and after 9 months of high-fat feeding in a canine model.

RESULTS

One night of total sleep deprivation in lean dogs impaired insulin sensitivity to a similar degree as a chronic high-fat diet (HFD)(normal sleep: 4.95 ± 0.45 mU-1 l-1 min-1; sleep deprivation: 3.14 ± 0.21 mU-1 l-1 min-1; HFD: 3.74 ± 0.48 mU-1 l-1 min-1; mean ± SEM). Hyperinsulinaemic compensation was induced by the chronic HFD, suggesting adequate beta cell response to high-fat feeding. In contrast, there was no beta cell compensation after one night of sleep deprivation, suggesting that there was metabolic dysregulation with acute sleep loss that, if sustained during chronic sleep loss, could contribute to the risk of type 2 diabetes. After chronic high-fat feeding, acute total sleep deprivation did not cause further impairments in insulin sensitivity (sleep deprivation + chronic HFD: 3.28 mU-1 l-1 min-1).

CONCLUSIONS/INTERPRETATION

Our findings provide further evidence that sleep is important for metabolic health and establish a diurnal animal model of metabolic disruption during insufficient sleep.

Late bedtime and dental caries incidence in Kuwaiti children: A longitudinal multilevel analysis

OBJECTIVE

Inadequate sleep contributes to several adverse systemic health outcomes due to hormonal and metabolic disorders. The purpose of this study was to determine the effect of bedtime on the development of dental caries and the relationship with salivary ghrelin and leptin in a prospective cohort study of Kuwaiti children.

METHODS

Data were collected from 5456 10-year-old children in 2012 and repeated in 2014. We selected children from 138 middle schools representing the six governorates of Kuwait. We derived data from oral examinations, self-reported sleep interviews, body and weight measurements, and chemical analysis of whole saliva samples. Leptin and ghrelin were determined by salivary assay in a subset of 744. Two separate analyses were performed. a) Using the entire longitudinal data set (n = 5456), multilevel random intercept analysis was conducted to assess the relationship between reported bedtime and dental caries. b) Using data from a subset of the original sample (n = 744), multiple linear regression analysis was conducted to determine the relationship between dental caries and salivary ghrelin and leptin. The outcome variable was the development of dental caries in children. The independent explanatory variables and confounders were bedtime, sleep duration, salivary ghrelin and leptin; confounders assessed were gingivitis, sex, age and governorate (school location).

RESULTS

With every additional hour past 8 pm for bedtime, there was a 20% increase in dental caries incidence over two years (B = 0.2, P = .01), adjusting for age, gender, gingivitis and governorate. There was a significant difference in the magnitude of dental caries between the six governorates of Kuwait. Lower levels of salivary leptin and higher levels of salivary ghrelin were associated with increased dental caries, and sleep duration was an effect modifier that negatively affected the relationship between leptin and dental caries (B = -0.09, P < .05) and positively affects the relationship between ghrelin and dental caries (B = 0.07, P < .05). Additionally, there was a significant clustering effect within schools in this cohort.

CONCLUSION

In a cohort study of Kuwaiti children, late bedtime was associated with increased dental caries incidence. Additionally, dental caries experience increased with higher levels of salivary ghrelin and lower levels of salivary leptin, and sleep duration mediates the relationship between these two biomarkers and dental caries.

Breakfast skipping is related to inadequacy of vitamin and mineral intakes among Japanese female junior high school students: a cross-sectional study

Breakfast skipping is a public health issue which affects nutrient intake among adolescents worldwide. However, there have been few reports comparing intake and reference values to assess the deficiency of nutrient intake between breakfast consumers and skippers. Therefore, the present study aimed to examine the relationship between breakfast skipping and adequacy of total habitual nutrient intake among junior high school female students. The participants were 516 Japanese female junior high school students. Dietary habits during the preceding month were assessed using a brief self-administered diet history questionnaire. Inadequacy of each nutrient intake was assessed by the cut-point method, based on the estimated average requirement for fourteen nutrients and on dietary goal values for five nutrients. The overall nutritional inadequacy in participants was assessed by the number of consumed nutrients which did not meet the requirements as per the dietary reference intakes for Japanese, 2015 version. The participants were classified into two groups according to the frequency of breakfast eating: breakfast consumers (seven times/week) and breakfast skippers (0-6 times/week). Adequacy of vitamin A, vitamin B1, vitamin B2, vitamin C, Ca, Fe, Zn and K was higher among breakfast consumers than among skippers. Breakfast consumers had more intakes of fruits, vegetables and dairy products. Our findings suggest that breakfast skipping was related to deficiencies in vitamin and mineral intakes, and to an unfavourable dietary pattern, among Japanese female junior high school students.

Acute Sleep Curtailment Increases Sweet Taste Preference, Appetite and Food Intake in Healthy Young Adults: A Randomized Crossover Trial

This study aimed to examine the effect of acute sleep curtailment on sweet taste preference, appetite and food intake, and the correlation between food intake and sweet taste preference or active ghrelin using a randomized crossover design (5 h sleep curtailment vs. 8 h control). Twenty-four participants (11 men) aged 21.4 ± 1.0 years, with BMI 19.8 ± 1.7 kg/m², who habitually slept 5 h/night or more experienced interventions lasting three consecutive nights. Participants came into the laboratory for testing on day 4. Fasting blood tests were conducted at 8:00 a.m. to measure active ghrelin and leptin levels. Sweet taste preference was assessed by presenting five different concentration sucrose solutions at 9:00 a.m. Ad libitum intake at breakfast was assessed for 30 min from 9:30 a.m. Sweet taste preference was higher following sleep curtailment than control. Active ghrelin was likewise higher following sleep curtailment than control. Leptin did not differ between conditions. Energy intake was higher following sleep curtailment than control, being derived primarily from carbohydrates. However, sweet taste preference and active ghrelin did not correlate with energy intake. These results suggest that acute consecutive sleep curtailment increases sweet taste preference, active ghrelin, and energy intake in healthy young adults.

Diet and sleep health: a scoping review of intervention studies in adults

BACKGROUND

Recent research has demonstrated an association between dietary intake and sleep health that can influence chronic disease risk factors. A scoping review of research studies investigating dietary intake and sleep was undertaken to determine the extent and scope of research in laboratory-based, free-living and mixed settings. Additionally, this review determines how well subpopulations and geographical locations are represented and the methodologies used to assess outcome measures.

METHODS

Five online databases were used to identify papers published between 1970 and 2017. Included studies were those conducted in adults and reported both outcomes of interest: (i) sleep health, including sleep restriction and sleep hygiene and (ii) dietary outcomes, including altered nutrients, dietary patterns and supplements.

RESULTS

In total, 129 publications were included with the majority being dietary interventions investigating sleep outcomes (n = 109) with fewer being sleep interventions investigating and reporting dietary outcomes (n = 20). Dietary interventions were most often carried out in free-living environments, in contrast to sleep interventions that were most often carried out in laboratory-based environments. The majority of dietary interventions investigated use of a supplement (n = 66 studies), which was predominantly caffeine (n = 49). Sleep interventions investigated sleep duration only, with the majority (n = 17) investigating the effect of partial sleep restriction under 5.5 h per night on dietary intake, while three studies investigating total sleep deprivation.

CONCLUSIONS

Investigating broader aspects of dietary such as overall diet quality and dietary patterns and other components of sleep health such as quality,  timing and sleep hygiene are important aspects for future research.

Association between diet quality and sleep apnea in the Multi-Ethnic Study of Atherosclerosis

Rationale

Although short sleep duration has been linked to unhealthy dietary patterns, little is known about the association of obstructive sleep apnea (OSA), a disorder characterized by sleep fragmentation and diet.

Study Objectives

Investigate associations between diet quality and OSA in the Multi-Ethnic Study of Atherosclerosis and assess whether reductions in slow-wave sleep (stage N3) and rapid eye movement (REM) sleep are potential mediators for these associations.

Methods

A diverse population (N = 1813) completed a food frequency questionnaire and underwent Type 2 in-home polysomnography, which included measurement of N3 and REM sleep and apnea-hypopnea index (AHI). Moderate-to-more severe OSA was defined as having an AHI > 15 events/hr.

Results

Participants were 53.9% female with a mean age of 68.3 (SD 9.1) years. Approximately 33.8% were categorized as having moderate-to-more severe OSA. In adjusted analyses, OSA was associated with lower intakes of whole grains, (β = -0.200, SE = 0.072, p < 0.01), higher intakes of red/processed meat, (β = -0.440, SE = 0.136, p < 0.01), and lower overall diet quality (β = -1.286, SE = 0.535, p = 0.02). Stage N3 sleep partially explained the associations between red/processed meat and overall diet quality score with OSA.

Conclusions

Moderate-to-more severe OSA is associated with a less healthy dietary profile that is partially explained by reduced N3 sleep. These findings suggest the opportunity to target sleep quality in interventions aimed at improving cardio-metabolic risk factors in patients with OSA.

Short Sleep, Insomnia, and Cardiovascular Disease

PURPOSE OF REVIEW

This review summarizes key findings linking insomnia, short sleep duration, and cardiovascular health.

RECENT FINDINGS

Early studies associations between insomnia with short sleep and cardiovascular disease Recent studies have incorporated objective data to assess sleep and identify comorbid sleep disorders (e.g. sleep apnea). Use of objective metrics has facilitated understanding of the impacts of insufficient sleep on autonomic dysregulation, metabolic syndrome, coronary artery disease and overall cardiovascular mortality. Emerging research suggests treatment of insomnia (CBT-I) may be beneficial in terms of reducing cardiovascular disease risk.

SUMMARY

From short term effects on the autonomic nervous system to lasting effects on metabolic syndrome and coronary artery disease, there is growing evidence to support a physiologic pathway by which insomnia with short sleep contributes to cardiovascular disease. More research is needed to understand the effect of insomnia treatment on cardiovascular risk.

Sleep duration is associated with healthy diet scores and meal patterns: results from the population-based EpiHealth study

STUDY OBJECTIVES

To investigate relationships between sleep duration and adherence to healthy diets, but also associations with meal patterns, in a large population-based cohort.

METHODS

Participants (n = 23,829, males and females, aged 45 to 75 years) from the Swedish EpiHealth cohort study were included in a cross-sectional analysis. The participants filled out an extensive Internet-based questionnaire, and also visited a test center for anthropometric measurements and blood sampling. Sleep duration was classified as short (< 6 h/night; n = 1,862), normal (6 to less fewer than 9 h/night; n = 19,907) and long sleep (≥ 9 h/night; n = 858). In addition, a combination variable of sleep duration (short/normal/long) and sleep quality (good/poor) was constructed, giving six categories. Adherence to a healthy diet was assessed using the modified Mediterranean diet (mMED) score and the Healthy Nordic Food Index (HNFI) score based on food groups from a food frequency questionnaire. A regular meal pattern was considered if the participant had breakfast, lunch and dinner on a daily basis.

RESULTS

Compared with normal sleepers, short sleepers displayed lower adherence to a healthy diet when using both the mMED score (adjusted odds ratio = 0.70; 95% confidence interval 0.56-0.88) and the HNFI score (0.70; 0.56-0.88). When combining sleep duration and sleep quality, short sleepers with poor sleep quality showed an independent relationship with low adherence to a healthy diet (0.67; 0.52-0.86) compared with normal sleepers with good sleep quality. In addition, both short sleepers (0.71; 0.62-0.82) and long sleepers (0.75; 0.62-0.91) showed low adherence to regular meal patterns, compared with normal sleepers. Furthermore, short sleepers with poor sleep quality had reduced odds of having a regular meal pattern (0.67; 0.57-0.79) as compared with normal sleepers with good sleep quality.

CONCLUSIONS

Short sleep duration combined with poor sleep quality is associated with low adherence to a healthy diet and regular meal patterns.

Prevalence of short sleep duration and effect of co-morbid medical conditions - A cross-sectional study in Saudi Arabia

Background:

Sleep is crucial to human's health and essential for a person's wellbeing. It is involved in multiple physiological mechanisms, such as metabolism, appetite regulation, immune and hormone function, and cardiovascular systems. The National Sleep Foundation recommends 7–9 h of sleep each night for adults. Short (<7 h) and long (<9 h) sleep duration has been reported to be associated with increased risk of morbidity and mortality.

Aim:

1) To assess the prevalence of short sleep durations among Saudi adult population. 2) To examine comorbid medical condition's association with short sleep duration.

Methods:

A nation-wide quantitative cross-sectional study using an online self-administered constructed questionnaire during the period from August to October 2018 was conducted. The questionnaire included demographic characters, such as age, gender, education level, height, and weight. As well as some of the participants’ habits such as consuming coffee and/or tea, smoking status, and other habits known to be associated with shorter sleep hours. The questionnaire also included self-reported duration of sleep and history of diagnosed medical illnesses.

Results:

The study included 805 adult Saudi participants with ages ranging from 15- to 60-year old and mean age of 21.8 ± 10.7-year old. About 63% of the participants were females. It was established that almost half 49.6% of the participants sleep for <7 h daily, and 39.3% of them sleep for 7–9 h.

Conclusion:

About half of Saudi adults do not get enough hours of sleep. Especially, people who are married, above 30-year old, students or tea drinkers (P < 0.05): furthermore, people with medical comorbidities such as anxiety, depression, and insomnia had a higher association with short sleep duration. Last, sleep deprivation adversely affects the physical wellbeing and quality of life of participants, demonstrated in bad mood, somnolence, and tiredness during the day time.

Olfactory connectivity mediates sleep-dependent food choices in humans

Sleep deprivation has marked effects on food intake, shifting food choices toward energy-dense options. Here we test the hypothesis that neural processing in central olfactory circuits, in tandem with the endocannabinoid system (ECS), plays a key role in mediating this relationship. We combined a partial sleep-deprivation protocol, pattern-based olfactory neuroimaging, and ad libitum food intake to test how central olfactory mechanisms alter food intake after sleep deprivation. We found that sleep restriction increased levels of the ECS compound 2-oleoylglycerol (2-OG), enhanced encoding of food odors in piriform cortex, and shifted food choices toward energy-dense food items. Importantly, the relationship between changes in 2-OG and food choices was formally mediated by odor-evoked connectivity between the piriform cortex and insula, a region involved in integrating feeding-related signals. These findings describe a potential neurobiological pathway by which state-dependent changes in the ECS may modulate chemosensory processing to regulate food choices.

People who do not get enough sleep often start to favor sweet and fatty foods, which contributes to weight gain. While the exact mechanisms are still unknown, lack of sleep seems to change food preferences by influencing the levels of molecules that regulate food intake. In particular, it could have an effect on the endocannabinoid system, a complex network of molecules in the nervous system that controls biological processes such as appetite.

The sense of smell is also tightly linked to how and what organisms choose to eat. Recent experiments indicate that in rodents, endocannabinoids enhance food intake by influencing the activity of the brain areas that process odors. However, it is still unclear whether the brain regions that process odors play a similar role in humans.

To investigate, Bhutani et al. examined the impact of a four-hour night’s sleep on 25 healthy human volunteers. Blood analyses showed that after a short night, individuals had increased amounts of 2-oleoylglycerol, a molecule that is part of the endocannabinoid system. When sleep-deprived people were given the choice to eat whatever they wanted, those with greater levels of 2-oleoylglycerol preferred food higher in energy. Bhutani et al. also imaged the volunteers’ brains to examine whether these changes were connected to modifications in the way the brain processed smells. This revealed that, in people who did not sleep enough, an odor-processing region called the piriform cortex was encoding smells more strongly.

The piriform cortex is connected to another region, the insula, which integrates information about the state of the body to control food intake. Lack of sleep altered this connection, and this was associated with a preference for high-energy food. In addition, further analysis showed that changes in the amounts of 2-oleoylglycerol were linked to modifications in the connection between the two brain areas. Taken together, these results suggest that sleep deprivation influences the endocannabinoid system, which in turn alters the connection between piriform and insular cortex, leading to a shift toward foods which are high in calories.

In the United States alone, one in three people sleep less than six hours a night. Learning more about how sleep deprivation affects brain pathways and food choice may help scientists to develop new drugs or behavioral therapies for conditions like obesity.

Associations Between Dietary Patterns and Sleep-Related Impairment in a Cohort of Community Physicians: A Cross-sectional Study

There is increasing evidence that diet can mitigate fatigue. The objective of this study was to assess the associations between dietary habits and sleep-related impairment (SRI) in a cohort of community physicians. In this cross-sectional study, we analyzed data from 245 physicians who had completed a wellness survey in March 2016 (98% response rate). Three dietary patterns were derived using principal component analysis: plant based, high protein, and high saturated fat and sugar. In the adjusted analysis, every SD increase in the plant-based dietary pattern score was associated with a 0.71-point decrease (β = -0.72; SE = 0.32; P = .027; 95% CI = -1.35 to -0.08) in the SRI score, and every SD increase in the high saturated fat and sugar dietary pattern score was associated with a 0.77-point increase (β = 0.77; SE = 0.32; P = .015; 95% CI = 0.15 to 1.39) in the SRI score. There were no associations between high protein diets and SRI scores. Physicians adhering to diets that are high in plant-based foods and low in saturated fat and added sugars had less SRI. Physicians currently face significant barriers to maintaining a healthy diet. This study highlights the potential role of workplace nutrition on SRI and work performance of physicians.

Bridging the Reciprocal Gap between Sleep and Fruit and Vegetable Consumption: A Review of the Evidence, Potential Mechanisms, Implications, and Directions for Future Work

A substantial burden of disease and mortality globally is attributable to both sleep disruption and low intakes of fruit and vegetable (FV) and there is increasing mechanistic and epidemiological evidence to support a reciprocal relationship between the two. This review provides an overview of experimental and observational studies assessing the relations between sleep and FV consumption from 52 human adult studies. Experimental studies are currently limited and show inconsistent results. Observational studies support a non-linear association with adults sleeping the recommended 7–9 hours/day having the highest intakes of FV. The potential mechanisms linking sleep and FV consumption are highlighted. Disrupted sleep influences FV consumption through homeostatic and non-homeostatic mechanisms. Conversely, FV consumption may influence sleep through polyphenol content via several potential pathways. Few human experimental studies have examined the effects of FV items and their polyphenols on sleep and there is a need for more studies to address this. An appreciation of the relationship between sleep and FV consumption may help optimize sleep and FV consumption and may reduce the burden of chronic diseases. This review provides implications for public health and directions for future work.

Effects of Two-Week Sleep Extension on Glucose Metabolism in Chronically Sleep-Deprived Individuals

STUDY OBJECTIVES

Sleep deprivation is known to be associated with insulin resistance and diabetes risk. This study investigated whether 2-week sleep extension in chronically sleep-deprived individuals would improve glucose metabolism.

METHODS

A crossover study was conducted in volunteers without diabetes who reported sleeping ≤ 6 h/night. They were randomized to maintain their habitual sleep or extend sleep time for 2 weeks, then crossed over after a washout period. Sleep was monitored by actigraphy. Oral glucose tolerance tests (75 g) with insulin levels was performed at the end of each period. Mixed-effect linear regression analysis, adjusting for sequence and period effects, was applied.

RESULTS

A total of 21 participants (19 females) with mean (standard deviation) age of 33.1 (6.1) years completed the protocol. Mean sleep duration during habitual sleep was 318.7 (44.3) minutes and the participants extended their sleep by 36.0 (45.2) minutes during sleep extension. The average washout period was 21 (11) days. There were no significant effects of sleep extension on any metabolic parameters. The per-protocol analysis included eight participants who could sleep more than 6 hours during sleep extension (mean sleep duration 396 [25] minutes, extended by 60.1 [28.5] minutes). Among these individuals, sleep extension improved Homeostatic Model Assessment of Insulin Resistance (adjusted mean difference -0.50 [95% confidence interval [CI] -0.89, -0.11, P = .013]), early insulin secretion (insulinogenic index; mean difference 0.39 [95% CI 0.15, 0.63, P = .001]), and β-cell function (disposition index, mean difference 1.07 [95% CI 0.17, 1.97, P = .02]).

CONCLUSIONS

Sleep extension in chronically sleep-deprived individuals improved glucose metabolism in only those who could objectively extend their sleep to more than 6 h/night. Our findings suggest that a critical amount of sleep is needed to benefit metabolic outcomes.

Sleep-an Essential Component of Obesity Screening and Counseling: A Policy Analysis of the Affordable Care Act

The Patient Protection and Affordable Care Act (PPACA) has provided access to health care for millions of people in the United States. One of the most beneficial aspects of the PPACA is the obesity screening and counseling provision. Currently, it is estimated that over 39% of US adults are obese. Research has linked sleep disturbances to obesity and obesity-related behaviors. The purpose of this article is to advocate for evidence-based care through the inclusion of sleep disturbance screening and management under the PPACA obesity screening and counseling provision. An in-depth policy analysis of the PPACA was conducted to examine the feasibility of adding sleep screenings to the obesity screening and counseling provision available under current law. Findings suggest that the adoption of this policy would require stakeholder advocacy and educational reform. Implementation of the policy would require additional economic investments, but the long-term savings could be significant. A campaign to raise awareness regarding the association between sleep disturbance and obesity among the public and health care professionals would be essential. Policy implementation would require interprofessional collaboration when performing sleep disordered screening and management. Preventative health care for individuals who have not previously accessed the health care system has the potential to socially and economically benefit society if policies provide for evidence-based care. Sleep screening and counseling is essential under the PPACA to adequately address the US obesity crisis.

Increased Hunger, Food Cravings, Food Reward, and Portion Size Selection after Sleep Curtailment in Women Without Obesity

This study examined the effects of one night of sleep curtailment on hunger, food cravings, food reward, and portion size selection. Women who reported habitually sleeping 7⁻9 h per night, were aged 18⁻55, were not obese, and had no sleep disorders were recruited. Sleep conditions in this randomized crossover study consisted of a normal night (NN) and a curtailed night (CN) where time in bed was reduced by 33%. Hunger, tiredness, sleep quality, sleepiness, and food cravings were measured. A progressive ratio task using chocolates assessed the food reward. Participants selected portions of various foods that reflected how much they wanted to eat at that time. The sleep duration was measured using a single-channel electroencephalograph. Twenty-four participants completed the study. The total sleep time was shorter during the CN (p < 0.001). Participants reported increased hunger (p = 0.013), tiredness (p < 0.001), sleepiness (p < 0.001), and food cravings (p = 0.002) after the CN. More chocolate was consumed after the CN (p = 0.004). Larger portion sizes selected after the CN resulted in increased energy plated for lunch (p = 0.034). In conclusion, the present study observed increased hunger, food cravings, food reward, and portion sizes of food after a night of modest sleep curtailment. These maladaptive responses could lead to higher energy intake and, ultimately, weight gain.

Reciprocal Roles of Sleep and Diet in Cardiovascular Health: a Review of Recent Evidence and a Potential Mechanism

PURPOSE OF REVIEW

This review investigates the potential bi-directional relation between sleep and diet in considering their contribution to cardiovascular health. We further explore the involvement of the gut microbiome in the relationships between poor sleep and dietary intakes and increased cardiovascular disease (CVD) risk.

RECENT FINDINGS

There is strong evidence that sleep restriction leads to unhealthy food choices and increased energy intake. The diet may impact sleep, as well. Epidemiological studies show that higher adherence to a Mediterranean dietary pattern predicts healthier sleep. One factor that could underlie these relationships is the gut microbiome. Although data are mixed, there is some evidence that sleep restriction can influence the composition of the gut microbiome in humans. Similarly, Mediterranean diets and other plant-rich diets are related to increased diversity of the microbiota. At present, few studies have investigated the influence of the microbiome on sleep; however, limited evidence from epidemiological and intervention studies suggest that the composition of the microbiome may relate to sleep quality. More research is needed to better understand the role of the microbiome in the multi-directional relationship between sleep, diet, and CVD. There is growing evidence of a bi-directional relationship between sleep and the diet, which could act in concert to influence CVD risk. Diets such as the Mediterranean diet, comprised of high intakes of fruits, vegetables, and other plant-based foods, may promote healthy sleep and beneficial gut microflora. The gut microbiome may then underlie the relation between diet, sleep, and CVD risk.

Relationship of evening meal with sleep quality in obese individuals with obstructive sleep apnea

PURPOSE

To determine the relationship between habitual food intake, resting energy expenditure and sleep pattern in obstructive sleep apnea (OSA) patients.

METHODS

Forty-five OSA obese males were included in the study. All participants were submitted to nocturnal polysomnography, body composition measurements by plethysmography, resting energy expenditure (REE) analysis by indirect calorimetry and they filled in a 3-day food record.

RESULTS

No differences in body composition, REE and food intake were found between the moderate and severe OSA groups. A trend towards higher energy intake in the severe OSA group was observed, compared to the moderate group (p = 0.08). Significant associations between apnea-hypopnea index (AHI) with body weight, body mass index (BMI) and resting energy expenditure (REE) were found. Higher food intake in the evening period was positively correlated with sleep stage NREM1, arousal index, and AHI and negatively correlated with sleep stage NREM3 and sleep efficiency. A multivariate linear regression showed energy intake at breakfast to be a significant negative predictor of AHI; protein intake (g/kg) showed a positive association, while energy intake at breakfast and at dinner were negative predictors of sleep efficiency; and energy intake at dinner was a negative predictor of stage NREM1 sleep.

CONCLUSIONS

We conclude that higher amounts of food intake during the evening period may diminish sleep quality in moderate and severe sleep apnea patients. In addition, despite observing no differences between OSA severity groups, a moderate correlation between REE and sleep quality and OSA exists.

Intensifying sleep slow oscillations does not improve metabolic control in healthy men

Impaired sleep quality and sleep loss compromise glucose homeostasis and metabolic function, but the mechanisms linking sleep and metabolic health are largely unclear. In order to gain insight into the relevance of specific electrophysiological sleep characteristics for metabolic control, we assessed the acute effect on glucose homeostasis as well as energy intake and expenditure of enhancing slow oscillatory activity, a hallmark of slow-wave sleep, by closed-loop auditory stimulation in healthy men. Twenty-two young, normal-weight men underwent an oral glucose tolerance test (oGTT), indirect calorimetry and the assessment of ad-libitum breakfast intake in the morning after nocturnal sleep with or without auditory stimulation in phase with the ongoing rhythmic occurrence of slow oscillation up-states during 210 min of slow-wave sleep in the first night-half. Stimulation vs. no stimulation strongly increased slow oscillatory activity without changing overall sleep structure, but did not alter fasting or oGTT-stimulated measures of glucose homeostasis. Food intake and energy expenditure were likewise comparable between conditions. Findings indicate that in healthy humans electrophysiological sleep quality is tuned to allow for optimal metabolic control. Future studies should investigate the potential of sleep stage-specific interventions to enhance metabolic control and well-being in patients with metabolic ailments.

Links between the circadian rhythm, obesity and the microbiome

Obesity is linked to a wide range of serious illnesses. In addition to the important impact on the health of the individual, obesity also has a substantial impact on the economy. Disruption of physiological day-night cycles could contribute to the increased incidence of obesity. According to the American National Sleep Federation, the percentage of the people who reported a sleep duration of six hours or less increased from 12 to 37 % over ten years. Insufficient sleep leads not only to an increase of the total calorie intake but changes the meal preference in favor of palatable foods and meals with high carbohydrate content. A decrease of leptin and increase of ghrelin levels caused by sleep deficiency can also play a role. In addition to the higher caloric intake, the timing of food consumption should be taken into account. The same meal eaten during the night versus the day is associated with increased postprandial glucose and triglyceride levels. The gut microbiome has also been recently understood as an endocrine system, with links between the gut microbiome and circadian rhythm changes possibly influencing increased obesity.

Metabolic and cardiovascular consequences of shift work: The role of circadian disruption and sleep disturbances

Shift work, defined as work occurring outside typical daytime working hours, is associated with an increased risk of various non-communicable diseases, including diabetes and cardiovascular disease. Disruption of the internal circadian timing system and concomitant sleep disturbances is thought to play a critical role in the development of these health problems. Indeed, controlled laboratory studies have shown that short-term circadian misalignment and sleep restriction independently impair physiological processes, including insulin sensitivity, energy expenditure, immune function, blood pressure and cardiac modulation by the autonomous nervous system. If allowed to persist, these acute effects may lead to the development of cardiometabolic diseases in the long term. Here, we discuss the evidence for the contributions of circadian disruption and associated sleep disturbances to the risk of metabolic and cardiovascular health problems in shift workers. Improving the understanding of the physiological mechanisms affected by circadian misalignment and sleep disturbance will contribute to the development and implementation of strategies that prevent or mitigate the cardiometabolic impact of shift work.

Overnight smartphone use: A new public health challenge? A novel study design based on high-resolution smartphone data

Background

Round-the-clock use of smartphones holds a potential for awakenings and/or shorter sleep duration, which may have adverse health consequences. We aim to describe overnight smartphone activity among young adults and to characterize those with smartphone interrupted sleep in terms of sleep impairment and mental and physical health indicators.

Methods

We use unique objective high-resolution information on timing of smartphone activity (based on >250,000 phone actions) continuously monitored over a four-week period among 815 young adults combined with indicators of mental and physical health.

Results

We find substantial overnight smartphone activity. More than 12% had smartphone activity in the middle of the night (3 to 5 hours after self-reported bedtime) and 41% had smartphone interrupted sleep on at least one weekday during a 4-week period. Those with frequent smartphone interrupted sleep had on average 48 minutes shorter self-reported sleep duration and higher body mass index, whereas there were no differences in physical or mental health symptoms.

Conclusions

The substantial smartphone activity during bed hours among young adults may pose a public health challenge and especially the relation to overweight warrants close attention.

Ghrelin, a gastrointestinal hormone, regulates energy balance and lipid metabolism

Ghrelin, an acylated peptide hormone of 28 amino acids, is an endogenous ligand of the released growth hormone secretagogue receptor (GHSR). Ghrelin has been isolated from human and rat stomach and is also detected in the hypothalamic arcuate nucleus. Ghrelin receptor is primarily located in the neuropeptide Y and agouti-related protein neurons. Many previous studies have shown that ghrelin and GHSR are involved in the regulation of energy homeostasis, and its administration can increase food intake and body weight gain. AMP-activated protein kinase is activated by ghrelin in the hypothalamus, which contributes to lower intracellular long-chain fatty acid level. Ghrelin appears to modulate the response to food cues via a neural network involved in the regulation of feeding and in the appetitive response to food cues. It also increases the response of brain areas involved in visual processing, attention, and memory to food pictures. Ghrelin is also an important factor linking the central nervous system with peripheral tissues that regulate lipid metabolism. It promotes adiposity by the activation of hypothalamic orexigenic neurons and stimulates the expression of fat storage-related proteins in adipocytes. Meanwhile, ghrelin exerts direct peripheral effects on lipid metabolism, including increase in white adipose tissue mass, stimulation of lipogenesis in the liver, and taste sensitivity modulation.

Daily associations between objective sleep and consumption of highly palatable food in free-living conditions

OBJECTIVES

Prior studies have shown that individuals with shorter sleep duration and later sleep timing consume more highly palatable food (HPF). It is unclear if this relationship exists at the within-individual level, e.g. if sleeping less or later on one night is associated with greater HPF consumption in the following day in naturalistic environments. This study examined the daily associations between naturalistic sleep and HPF consumption.

METHODS

Data were obtained from 78 healthy young adults (age = 20.38 [SD = 2.40] years). Participants carried a wrist actigraph and completed daily diaries tracking food consumption and covariates for seven consecutive days. Data were analysed using mixed models.

RESULTS

Individuals with later bedtime were less likely to consume HPF at breakfast in the following day (odds ratio, OR [between] = 0.55 [0.44, 0.70], p < 0.001). This association was also significant at the within-individual level (OR (within) = 0.85 [0.74, 0.97], p = 0.016) - sleeping later on one night was associated with 15% decrease in the odds of consuming HPF at breakfast in the following day. Individual with later wake time had greater likelihood of consuming HPF at dinner (OR = 1.34 [1.03, 1.75], p = 0.027).

CONCLUSIONS

Sleep schedules characterized by later bedtimes and later wake times were associated with lower HPF consumption earlier in the following day but greater HPF consumption later in the day. This pattern of energy intake might mediate the association between sleep and the risk of obesity.

Role of Leptin in Obstructive Sleep Apnea

Leptin is a peptide hormone produced mainly in white adipose tissue. It is known to regulate energy homeostasis, inflammation, metabolism, and sympathetic nerve activity. Increasing evidence suggests it has a role in ventilatory function and upper airway obstruction. Leptin levels correlate positively with measurements of adiposity and can potentially provide important insights into the pathophysiology of diseases associated with obesity. Obesity is a strong risk factor for obstructive sleep apnea, a disease characterized by periodic upper airway occlusion during sleep. The neuromuscular activity that maintains upper airway patency during sleep and the anatomy of upper airway are key factors involved in its pathogenesis. Experimental studies using animal models of a low leptin state such as leptin deficiency have shown that leptin regulates sleep architecture, upper airway patency, ventilatory function, and hypercapnic ventilatory response. However, findings from human studies do not consistently support the data from the animal models. The effect of leptin on the pathophysiology of obstructive sleep apnea is being investigated, but the results of studies have been confounded by leptin's diurnal variation and the short-term effects of feeding, adiposity, age, and sex. Improved study design and methods of assessing functional leptin levels, specifically their central versus peripheral effects, will improve understanding of the role of leptin in sleep apnea.

Objective Sleep Characteristics and Cardiometabolic Health in Young Adolescents

: media-1vid110.1542/5778442247001PEDS-VA_2017-4085Video Abstract BACKGROUND AND OBJECTIVES: Shorter sleep duration is associated with childhood obesity. Few studies measure sleep quantity and quality objectively or examine cardiometabolic biomarkers other than obesity.

METHODS

This cross-sectional study of 829 adolescents derived sleep duration, efficiency and moderate-to-vigorous physical activity from >5 days of wrist actigraphy recording for >10 hours/day. The main outcome was a metabolic risk score (mean of 5 sex-specific z-scores for waist circumference, systolic blood pressure, high-density lipoprotein cholesterol scaled inversely, and log-transformed triglycerides and homeostatic model assessment of insulin resistance), for which higher scores indicate greater metabolic risk. Secondary outcomes included score components and dual-energy radiograph absorptiometry fat mass. We measured socioeconomic status, race and/or ethnicity, pubertal status, and obesity-related behaviors (television-viewing and fast food and sugar-sweetened beverage consumption) using questionnaires.

RESULTS

The sample was 51.5% girls; mean (SD) age 13.2 (0.9) years, median (interquartile range) sleep duration was 441.1 (54.8) minutes per day and sleep efficiency was 84.0% (6.3). Longer sleep duration was associated with lower metabolic risk scores (-0.11 points; 95% CI: -0.19 to -0.02, per interquartile range). Associations with sleep efficiency were similar and persisted after adjustment for BMI z score and physical activity, television-viewing, and diet quality. Longer sleep duration and greater sleep efficiency were also favorably associated with waist circumference, systolic blood pressure, high-density lipoprotein cholesterol, and fat mass.

CONCLUSIONS

Longer sleep duration and higher sleep efficiency were associated with a more favorable cardiometabolic profile in early adolescence, independent of other obesity-related behaviors. These results support the need to assess the role of sleep quantity and quality interventions as strategies for improving cardiovascular risk profiles of adolescents.

Sleep influences on obesity, insulin resistance, and risk of type 2 diabetes

A large body of epidemiologic evidence has linked insufficient sleep duration and quality to the risk of obesity, insulin resistance and type 2 diabetes. To address putative causal mechanisms, this review focuses on laboratory interventions involving several nights of experimental sleep restriction, fragmentation or extension and examining metabolically relevant outcomes. Sleep restriction has been consistently shown to increase hunger, appetite and food intake, with the increase in caloric intake in excess of the energy requirements of extended wakefulness. Findings regarding decreases in hormones promoting satiety or increases in hormones promoting hunger have been less consistent, possibly because of confounding effects of changes in adiposity when energy intake was not controlled and sampling protocols that did not cover the entire 24-h cycle. Imaging studies revealed alterations in neuronal activity of brain regions involved in food reward. An adverse impact of experimental sleep restriction on insulin resistance, leading to reduced glucose tolerance and increased diabetes risk, has been well-documented. There is limited evidence indicating that sleep fragmentation without reduction in sleep duration also results in a reduction in insulin sensitivity. The adverse metabolic outcomes of sleep disturbances appear to involve multiple mechanistic pathways acting in concert. Emerging evidence supports the benefits of behavioral, but not pharmacological, sleep extension on appetite and glucose metabolism. Further research should focus on the feasibility and efficacy of strategies to optimize sleep duration and quality on obesity and diabetes risk in at-risk populations as well as those with established diseases. Further work is needed to identify mechanistic pathways.

Chronic Insufficient Sleep Has a Limited Impact on Circadian Rhythmicity of Subjective Hunger and Awakening Fasted Metabolic Hormones

Weight gain and obesity have reached epidemic proportions in modern society. Insufficient sleep-which is also prevalent in modern society-and eating at inappropriate circadian times have been identified as risk factors for weight gain, yet the impact of chronic insufficient sleep on the circadian timing of subjective hunger and physiologic metabolic outcomes are not well understood. We investigated how chronic insufficient sleep impacts the circadian timing of subjective hunger and fasting metabolic hormones in a 32-day in-laboratory randomized single-blind control study, with healthy younger participants (range, 20-34 years) randomized to either Control (1:2 sleep:wake ratio, 6.67 h sleep:13.33 h wake, n = 7, equivalent to 8 h of sleep per 24 h) or chronic sleep restriction (CSR, 1:3.3 sleep:wake ratio, 4.67 h sleep:15.33 h wake, n = 8, equivalent to 5.6 h of sleep per 24 h) conditions. Participants lived on a "20 h day" designed to distribute all behaviors and food intake equally across all phases of the circadian cycle over every six consecutive 20 h protocol days. During each 20 h day, participants were provided a nutritionist-designed, isocaloric diet consisting of 45-50% carbohydrate, 30-35% fat, and 15-20% protein adjusted for sex, weight, and age. Subjective non-numeric ratings of hunger were recorded before and after meals and fasting blood samples were taken within 5 min of awakening. Subjective levels of hunger and fasting concentrations of leptin, ghrelin, insulin, glucose, adiponectin, and cortisol all demonstrated circadian patterns; there were no differences, however, between CSR and Control conditions in subjective hunger ratings or any fasting hormone concentrations. These findings suggest that chronic insufficient sleep may have a limited role in altering the robust circadian profile of subjective hunger and fasted metabolic hormones.

CLINICAL TRIAL REGISTRATION

The study was registered as clinical trial #NCT01581125.

Does stress influence sleep patterns, food intake, weight gain, abdominal obesity and weight loss interventions and vice versa?

Decades of research have reported only weak associations between the intakes of specific foods or drinks and weight gain and obesity. Randomized controlled dietary intervention trials have only shown very modest effects of changes in nutrient intake and diet composition on body weight in obese subjects. This review summarizes the scientific evidence on the role mental stress (either in or not in association with impaired sleep) may play in poor sleep, enhanced appetite, cravings and decreased motivation for physical activity. All these factors contribute to weight gain and obesity, possibly via decreasing the efficacy of weight loss interventions. We also review evidence for the role that lifestyle and stress management may play in achieving weight loss in stress-vulnerable individuals with overweight.

The Relationship Among Morningness-Eveningness, Sleep Duration, Social Jetlag, and Body Mass Index in Asian Patients With Prediabetes

Background: Circadian system is known to influence energy metabolism. Recent evidence suggested that evening preference could be associated with higher body mass index (BMI). Moreover, evening preference is known to be associated with insufficient sleep duration and greater social jetlag, both described to be associated with obesity. This study aimed to explore whether morningness-eveningness was directly associated with BMI or its effect was transmitted through sleep duration or social jetlag in patients with prediabetes. Methods: A total 2,133 patients with prediabetes were enrolled. Morningness-eveningness was assessed using a Composite Scale of Morningness (CSM). Average weekly sleep duration and sleep timing were obtained, and social jetlag was calculated. BMI was calculated by weight (kg)/height² (m²). A mediation analysis was performed based on two pathways, i.e. CSM→sleep→duration→BMI and CSM→social jetlag→BMI. A sequential equation model was used to estimate the direct and indirect effects of CSM on BMI. Results: Mean (SD) age and BMI were 63.6 (9.2) years and 25.8 (4.0) kg/m². For CSM→sleep duration→BMI pathway, every one point decrease in CSM (more evening preference) was associated with a decrease in sleep duration by 0.054 h (95% CI 0.043-0.066), whereas sleep duration was negatively associated with BMI (coefficient = -0.156, 95%CI -0.288, -0.024). Mediation analysis indicated that a change in CSM (from 90th to 10th percentile, more evening preference) was associated with a decrease in sleep duration and an increase in BMI by 0.102 kg/m² (95% CI 0.015, 0.207). In addition, this change in CSM was directly associated with an increase in BMI by 0.511 kg/m² (95%CI 0.030, 0.952). The CSM→social jetlag→BMI pathway analysis revealed that social jetlag was not significantly associated with BMI. A subgroup analysis in those aged ≤60 years (n = 784) revealed that each hour increase in social jetlag was associated with an increase in BMI by 0.56 kg/m² (p = 0.026) while CSM and sleep duration were not. Conclusion: In patients with prediabetes, more evening preference was directly associated with higher BMI and indirectly through insufficient sleep duration, while social jetlag did not mediate the relationship between CSM and BMI. In those ≤60 years, only greater social jetlag was associated with higher BMI. These data could inform further interventional studies to reduce BMI in this high risk group.

Gut: A key player in the pathogenesis of type 2 diabetes?

The gut regulates glucose and energy homeostasis; thus, the presence of ingested nutrients into the gut activates sensing mechanisms that affect both glucose homeostasis and regulate food intake. Increasing evidence suggest that gut may also play a key role in the pathogenesis of type 2 diabetes which may be related to both the intestinal microbiological profile and patterns of gut hormones secretion. Intestinal microbiota includes trillions of microorganisms but its composition and function may be adversely affected in type 2 diabetes. The intestinal microbiota may be responsible of the secretion of molecules that may impair insulin secretion/action. At the same time, intestinal milieu regulates the secretion of hormones such as GLP-1, GIP, ghrelin, gastrin, somatostatin, CCK, serotonin, peptide YY, GLP-2, all of which importantly influence metabolism in general and in particular glucose metabolism. Thus, the aim of this paper is to review the current evidence on the role of the gut in the pathogenesis of type 2 diabetes, taking into account both hormonal and microbiological aspects.

Sleep timing is associated with self-reported dietary patterns in 9- to 15-year-olds

OBJECTIVE

To examine sleep timing differences in self-reported dietary patterns of children and adolescents.

DESIGN

Cross-sectional.

PARTICIPANTS

Students aged 9-15 years (n=119, 11.7±1.3 years, 76% female) attending a summer program for the gifted. The upper and lower quartiles of reported midsleep time (weighted weekday-weekend average) were used to identify early (n=28) and late (n=27) sleep timing groups.

METHODS

Sleep patterns were assessed via self-report. Participants also rated their likelihood to consume 9 different categories of food and drinks on a 5-point scale ranging from "no likelihood" to "high likelihood." Foods were grouped as follows: (1) sugary and caffeinated beverages; (2) high-energy-dense, nutrient-poor foods (ie, sugary, salty, fatty foods); and (3) low-energy-dense, nutrient-rich foods (ie, vegetables, proteins, carbohydrates, fruits).

RESULTS

Midsleep time was 02:11±00:25 for the early and 06:14±01:00 for the late sleep timing groups. Participants reporting later sleep timing were more likely to consume sugary/caffeinated beverages and high-energy-dense, nutrient-poor foods throughout the day compared with their early sleep timing peers. The late vs the early sleep timing group also had a higher likelihood of overall consumption of foods and drinks from all categories into the evening and nighttime hours.

CONCLUSION

Our findings indicate that children and adolescents who exhibit late sleep timing are more likely to make poorer dietary choices, which may have important implications for understanding pathways to adiposity and obesity risk during this sensitive period of development.

Role of sleep and circadian disruption on energy expenditure and in metabolic predisposition to human obesity and metabolic disease

Weight gain, obesity and diabetes have reached alarming levels in the developed world. Traditional risk factors such as over-eating, poor nutritional choices and lack of exercise cannot fully account for the high prevalence of metabolic disease. This review paper examines the scientific evidence on two novel risk factors that contribute to dys-regulated metabolic physiology: sleep disruption and circadian misalignment. Specifically, fundamental relationships between energy metabolism and sleep and circadian rhythms and the impact of sleep and circadian disruption on metabolic physiology are examined. Millions of individuals worldwide do not obtain sufficient sleep for healthy metabolic function, and many participate in shift work and social activities at times when the internal physiological clock is promoting sleep. These behaviours predispose an individual for poor metabolic health by promoting excess caloric intake in response to reduced sleep, food intake at internal biological times when metabolic physiology is not prepared, decreased energy expenditure when wakefulness and sleep are initiated at incorrect internal biological times, and disrupted glucose metabolism during short sleep and circadian misalignment. In addition to the traditional risk factors of poor diet and exercise, disturbed sleep and circadian rhythms represent modifiable risk factors for prevention and treatment of metabolic disease and for promotion of healthy metabolism.

Phenotypic Stability of Energy Balance Responses to Experimental Total Sleep Deprivation and Sleep Restriction in Healthy Adults

Experimental studies have shown that sleep restriction (SR) and total sleep deprivation (TSD) produce increased caloric intake, greater fat consumption, and increased late-night eating. However, whether individuals show similar energy intake responses to both SR and TSD remains unknown. A total of N = 66 healthy adults (aged 21–50 years, 48.5% women, 72.7% African American) participated in a within-subjects laboratory protocol to compare daily and late-night intake between one night of SR (4 h time in bed, 04:00–08:00) and one night of TSD (0 h time in bed) conditions. We also examined intake responses during subsequent recovery from SR or TSD and investigated gender differences. Caloric and macronutrient intake during the day following SR and TSD were moderately to substantially consistent within individuals (Intraclass Correlation Coefficients: 0.34–0.75). During the late-night period of SR (22:00–04:00) and TSD (22:00–06:00), such consistency was slight to moderate, and participants consumed a greater percentage of calories from protein (p = 0.01) and saturated fat (p = 0.02) during SR, despite comparable caloric intake (p = 0.12). Similarly, participants consumed a greater percentage of calories from saturated fat during the day following SR than TSD (p = 0.03). Participants also consumed a greater percentage of calories from protein during recovery after TSD (p < 0.001). Caloric intake was greater in men during late-night hours and the day following sleep loss. This is the first evidence of phenotypic trait-like stability and differential vulnerability of energy balance responses to two commonly experienced types of sleep loss: our findings open the door for biomarker discovery and countermeasure development to predict and mitigate this critical health-related vulnerability.

Circadian Rhythm and Sleep Disruption: Causes, Metabolic Consequences, and Countermeasures

Circadian (∼24-hour) timing systems pervade all kingdoms of life and temporally optimize behavior and physiology in humans. Relatively recent changes to our environments, such as the introduction of artificial lighting, can disorganize the circadian system, from the level of the molecular clocks that regulate the timing of cellular activities to the level of synchronization between our daily cycles of behavior and the solar day. Sleep/wake cycles are intertwined with the circadian system, and global trends indicate that these, too, are increasingly subject to disruption. A large proportion of the world's population is at increased risk of environmentally driven circadian rhythm and sleep disruption, and a minority of individuals are also genetically predisposed to circadian misalignment and sleep disorders. The consequences of disruption to the circadian system and sleep are profound and include myriad metabolic ramifications, some of which may be compounded by adverse effects on dietary choices. If not addressed, the deleterious effects of such disruption will continue to cause widespread health problems; therefore, implementation of the numerous behavioral and pharmaceutical interventions that can help restore circadian system alignment and enhance sleep will be important.

Disturbances of sleep and circadian rhythms: novel risk factors for obesity

PURPOSE OF REVIEW

The purpose of this review is to summarize recent developments linking disturbances of sleep and circadian rhythms to an increased risk for obesity, and to review novel research on potential countermeasures.

RECENT FINDINGS

Effective treatments for obesity are limited, with long-term adherence to lifestyle changes proving difficult to maintain. Identifying new preventive strategies based on modifiable risk factors is therefore imperative in the fight against obesity. Disturbances of sleep and circadian rhythms have an adverse impact on food choices, hunger and appetite, and have lifelong deleterious metabolic consequences when they occur during childhood and early adulthood. The upregulation of the endocannabinoid system and abnormalities in the temporal distribution of caloric intake were recently implicated in the link between sleep loss and obesity risk. In addition, alterations in circadian variation in the composition and functionality of the gut microbiome have been identified as potential contributors to metabolic dysfunction during jet lag and shift work. Insufficient sleep and circadian misalignment are thus new modifiable risk factors for obesity. Emerging evidence suggests that novel countermeasures, such as manipulations of the timing of food intake, may be effective strategies in the prevention of obesity.

SUMMARY

Four important findings are briefly reviewed: disturbances of sleep and circadian rhythms in children and young adults are risk factors for the development of lifelong obesity; circadian misalignment, as occurs in shift work, has an adverse impact on energy balance and increases the risk of weight gain; the endocannabinoid system, an important regulator of hedonic feeding, could be a potential link between sleep, circadian rhythms, and feeding behavior; and disturbances of the circadian variation in composition of the gut microbiome may be involved in the increased risk of obesity associated with insufficient sleep and circadian misalignment.