Effects of sleep extension on sleep duration, sleepiness, and blood pressure in college students

What are the important risk factors for excessive daytime sleepiness in a population-based cohort?

Excessive daytime sleepiness (EDS) is a common complaint in the general population and is associated with cardiovascular disease and increased mortality. We aimed to investigate whether sleep duration is related to excessive daytime sleepiness in the general population, both in itself and in combination with other factors. We performed a cross-sectional analysis in the population-based Swedish CArdioPulmonary bioImage Study (SCAPIS) cohort (n = 27,976; 14,436 females; aged 50-64 years) to assess how sleep-related factors along with anthropometric, lifestyle, socioeconomic factors as well as somatic disease and psychological distress, were related with EDS assessed by the Epworth sleepiness scale (ESS). Analyses were performed using logistic regression modelling with EDS defined by an ESS score of ≥11 as the main outcome. Both short and long sleep duration were related to EDS with increasing ORs for decreasing sleep duration (7 h vs. reference (8 h): OR 1.2, 95% CI 1.02-1.3 to ≤4 h: 1.9; 1.4-2.5). In addition to sleep-related factors such as insomnia (1.3; 1.2-1.4), poor sleep quality (1.2; 1.04-1.4), snoring (1.5; 1.4-1.6), and nocturnal gastro-oesophageal reflux (1.5; 1.21-1.8), psychological distress showed a strong association with EDS. This included sadness/depression (1.2; 1.1-1.3), stress (some stress: 1.4; 1.1-1.7 to constant stress over 5 years: 1.7; 1.3-2.2), and self-rated "control in life" (lowest quartile: 1.7; 1.6-2.0). Daytime sleepiness is multifactorial and associated with both sleep duration and sleep quality. Strong associations were also established with factors related to psychological distress. Further research may investigate interventions targeting both sleep and psychological health to reduce daytime sleepiness at the societal level.

Sleep Deficiency and Cardiometabolic Disease

Epidemiologic studies have demonstrated that short sleep duration is associated with an increased risk of cardio-metabolic health outcomes including cardiovascular disease mortality, coronary heart disease, type 2 diabetes mellitus, hypertension, and metabolic syndrome. Experimental sleep restriction studies have sought to explain these findings. This review describes the main evidence of these associations and possible mechanisms explaining them. Whether sleep extension reverses these now widely acknowledged adverse health effects and the feasibility of implementing such strategies on a public health level is discussed.

Sleep extension and cardiometabolic health: what it is, possible mechanisms and real-world applications

Short sleep duration is associated with heightened cardiometabolic disease risk and has reached epidemic proportions among children, adolescents and adults. Potential mechanisms underlying this association are complex and multifaceted, including disturbances in circadian timing, food intake and appetitive hormones, brain regions linked to control of hedonic eating, physical activity, an altered microbiome and impaired insulin sensitivity. Sleep extension, or increasing total sleep duration, is an emerging and ecologically relevant intervention with significant potential to advance our understanding of the mechanisms underlying the association between short sleep duration and the risk of cardiometabolic disease. If effective, sleep extension interventions have potential to improve cardiometabolic health across the lifespan. Existing data show that sleep extension is feasible and might have potential cardiometabolic health benefits, although there are limitations that the field must overcome. Notably, most existing studies are short term (2-8 weeks), use different sleep extension strategies, analyse a wide array of cardiometabolic health outcomes in different populations and, frequently, lack adequate statistical power, thus limiting robust scientific conclusions. Overcoming these limitations will require fully powered, randomized studies conducted in people with habitual short sleep duration and existing cardiometabolic risk factors. Additionally, randomized controlled trials comparing different sleep extension strategies are essential to determine the most effective interventions. Ongoing and future research should focus on elucidating the potential cardiometabolic health benefits of sleep extension. Such studies have high potential to generate crucial knowledge with potential to improve health and quality of life for those struggling with short sleep duration.

Sleep Disturbances in Type 1 Diabetes and Mitigating Cardiovascular Risk

Cardiovascular disease (CVD) is a major cause of morbidity and mortality in persons with type 1 diabetes (T1D). Despite control of known cardiovascular (CV) risk factors and better glycemic management, persons with T1D still face heightened CVD risk, suggesting additional contributing factors. Sleep has recently been recognized as a CV risk factor; however; the role of sleep in CVD specifically in T1D population has only started to emerge. Extensive evidence suggests that persons with T1D often encounter sleep disturbances. This review aims to comprehensively explore the relationship between sleep disturbances and CVD in T1D, proposed possible mediators including glycemic control, which has been studied more extensively, and less studied factors such as blood pressure, lipid metabolism, and weight management. Stress and self-care behaviors likely also play a role in the relationship between sleep disturbances and CVD. The evidence regarding sleep interventions in the context of T1D in mitigating these CV risk factors has recently been shown in early, small-scale studies. Sleep assessments should be a part of the standard of care in persons with T1D. Further research should focus on understanding the impact and mechanistic pathways of sleep disturbances on CV risk and developing T1D-specific sleep interventions to reduce CVD burden in this population.

Associations of actigraph sleep characteristics with blood pressure among older adults

OBJECTIVES

Many studies have examined links between sleep and blood pressure, with mixed findings, mostly using self-reported sleep data and cross-sectional designs. We examined whether actigraph-estimated sleep characteristics are associated with concurrent blood pressure or 5-year blood pressure change in a national cohort of older adults (National Social Life, Health and Aging Project), and whether these associations differ by hypertension medication use.

METHODS

Subjects were 669 older adults (62-90years), 471 with 5-year follow-up data. Sleep characteristics were duration (linear plus quadratic terms); sleep percentage; and categorical onset, midpoint, and waking times. Multivariable linear models adjusted for age, race, gender, obesity, smoking, daytime napping, and hypertension medication use. Interactions between sleep characteristics and hypertension medication were tested among the 401 subjects with consistent hypertension medication status over time.

RESULTS

We found U-shaped cross-sectional and longitudinal relationships between duration and blood pressure, with shorter and longer sleep times associated with higher blood pressure. Later onset times were cross-sectionally associated with higher systolic blood pressure, while earlier onset times were longitudinally associated with systolic blood pressure increase. Midpoint, wake time, and sleep percentage were not significantly associated with blood pressure. Significant interaction terms suggested hypertension medications attenuated associations of sleep onset and wake time with diastolic blood pressure.

CONCLUSIONS

These results with actigraph-estimated parameters confirm some, but not all, associations reported from research based on self-reported sleep data. Our findings are consistent with recommended intermediate sleep durations for cardiovascular health and suggest hypertension medication use may attenuate some associations between sleep timing and blood pressure.

Reducing crash risk for young drivers: Protocol for a pragmatic randomised controlled trial to improve young driver sleep

Background

Road trauma is a leading cause of death and disability for young Australians (15-24 years). Young adults are overrepresented in crashes due to sleepiness, with two-thirds of their fatal crashes attributed to sleepy driving. This trial aims to examine the effectiveness of a sleep extension and education program for improved road safety in young adults.

Methods

Young adults aged 18-24 years (n = 210) will be recruited for a pragmatic randomised controlled trial employing a placebo-controlled, parallel-groups design. The intervention group will undergo sleep extension and receive education on sleep, whereas the placebo control group will be provided with information about diet and nutrition. The primary outcomes of habitual sleep and on-road driving performance will be assessed via actigraphy and in-vehicle accelerometery. A range of secondary outcomes including driving behaviours (driving simulator), sleep (diaries and questionnaire) and socio-emotional measures will be assessed.

Discussion

Sleep is a modifiable factor that may reduce the risk of sleepiness-related crashes. Modifying sleep behaviour could potentially help to reduce the risk of young driver sleepiness-related crashes. This randomised control trial will objectively assess the efficacy of implementing sleep behaviour manipulation and education on reducing crash risk in young adult drivers.

Shared genetic architecture and causal relationship between sleep behaviors and lifespan

Poor sleep health is associated with a wide array of increased risk for cardiovascular, metabolic and mental health problems as well as all-cause mortality in observational studies, suggesting potential links between sleep health and lifespan. However, it has yet to be determined whether sleep health is genetically or/and causally associated with lifespan. In this study, we firstly studied the genome-wide genetic association between four sleep behaviors (short sleep duration, long sleep duration, insomnia, and sleep chronotype) and lifespan using GWAS summary statistics, and both sleep duration time and insomnia were negatively correlated with lifespan. Then, two-sample Mendelian randomization (MR) and multivariable MR analyses were applied to explore the causal effects between sleep behaviors and lifespan. We found that genetically predicted short sleep duration was causally and negatively associated with lifespan in univariable and multivariable MR analyses, and this effect was partially mediated by coronary artery disease (CAD), type 2 diabetes (T2D) and depression. In contrast, we found that insomnia had no causal effects on lifespan. Our results further confirmed the negative effects of short sleep duration on lifespan and suggested that extension of sleep may benefit the physical health of individuals with sleep loss. Further attention should be given to such public health issues.

Effects of a 1-hour per night week-long sleep extension in college students on cardiometabolic parameters, hydration status, and physical activity: A pilot study

OBJECTIVES

Short sleep duration is associated with poor physical health in college students. Few studies examine the effects of sleep extension on physical health in this population, who are susceptible to sleep loss. We examined health effects of a 1-week, 1-hour nightly sleep extension in college students.

METHODS

Twelve healthy undergraduate college students (83% female; age 20.2 ± 1.5years) completed a study consisting of sleeping typically for 1week ("Habitual"), then extending sleep by ≥1 hour/night during the second week ("Extension"). Sleep and physical activity actigraphy were collected throughout. Following each week, participants completed cardiometabolic assessments including a meal response and provided a urine sample for markers of hydration.

RESULTS

In Extension compared to Habitual, average sleep duration increased (mean change±SEM, +42.6 ± 15.1 minutes; p = .005), while subjective sleepiness (-1.8 ± 0.8 units; p = .040), systolic blood pressure (-6.6 ± 2.8 mmHg; p = .037), postprandial glucose area under the curve (-26.5 ± 10.2 mg/dL × h; p = .025) and time to baseline (-83.0 ± 46.4 minutes; p = .031) after the meal response, sedentary time (-44.3 ± 15.7 minutes; p = .018), and percentage of wake in moderate-to-vigorous activity (-0.89% ± 0.35%; p = .030) decreased. Participants who increased average sleep duration by ≥20 minutes (n = 9) were better hydrated according to urine osmolality (-187.0 ± 68.4 mOsm/kg; p = .026) and specific gravity (-0.01 ± 0.002 g/mL; p = .012) and had reduced odds of dehydration according to urine osmolality (≥800 mOsm/kg; -67%; OR=0.03; p = .035).

CONCLUSIONS

This pilot study's findings suggest that sleep extension may improve cardiometabolic functioning and hydration, and alter sedentary behavior and physical activity, in college students. Sleep extension may be employed to improve multiple aspects of health in this sleep-deprived population.

Salty Subjects: Unpacking Racial Differences in Salt-Sensitive Hypertension

PURPOSE OF REVIEW

To review underlying mechanisms and environmental factors that may influence racial disparities in the development of salt-sensitive blood pressure.

RECENT FINDINGS

Our group and others have observed racial differences in diet and hydration, which may influence salt sensitivity. Dietary salt elicits negative alterations to the gut microbiota and immune system, which may increase hypertension risk, but little is known regarding potential racial differences in these physiological responses. Antioxidant supplementation and exercise offset vascular dysfunction following dietary salt, including in Black adults. Furthermore, recent work proposes the role of racial differences in exposure to social determinants of health, and differences in health behaviors that may influence risk of salt sensitivity. Physiological and environmental factors contribute to the mechanisms that manifest in racial differences in salt-sensitive blood pressure. Using this information, additional work is needed to develop strategies that can attenuate racial disparities in salt-sensitive blood pressure.

The association between sleep deprivation and the risk of cardiovascular diseases: A systematic meta‑analysis

Globally, sleep deprivation is a concerning health issue associated with an increased risk of cardiovascular diseases (CVDs). The present study aimed to explore the association between short-term sleep and the risk of CVDs, taking into consideration sex and age groups. A comprehensive review was conducted by assembling cohort studies that are available in the PubMed, Cochrane Library, and Embase databases. Individuals with ≤5 or ≤6 h of sleep per day were considered as sleep-deprived subjects. To minimize potential bias, two reviewers thoroughly evaluated the selected articles. Relevant data were extracted, and pooled odds ratios (ORs) or relative risks (RRs) were calculated using a random-effects model. In total, 18 cohort studies involving adult subjects were included in the present analysis. The pooled results strongly indicated that sleep deprivation was associated with a greater risk of CVDs [RR: 1.09, 95% confidence interval (CI): 1.02-1.16, P=0.009]. However, when the pooled analysis was stratified by sex and age, the following results were observed: short-term sleep women (RR: 1.06, 95% CI: 0.96-1.17, P=0.27), short-term sleep men (RR: 1.07, 95% CI: 0.97-1.17, P=0.17); ≥18 years-old sleep-deprived population (RR: 1.09, 95% CI: 1.00-1.17, P=0.04), ≥40 years-old sleep-deprived population (RR: 1.09, 95% CI: 0.98-1.22, P=0.11), and subjects with co-existing diseases, such as diabetes and hyperlipidemia (RR: 1.06, 95% CI: 0.94-1.20, P=0.32). In conclusion, short-term sleep is associated with the increased risk of CVDs. Among subjects who were aged ≥18 years-old, there was a strong association with the development of CVDs compared with those who were aged ≥40 years-old. Furthermore, men were at a higher risk of CVDs than women. Adequate sleep (7-8 h per day) may play a role in improving cardiac health. The results of the present study may provide valuable support for further research in public health, highlighting the correlation between sleep deprivation and the risk of CVDs.

Examining the U-shaped relationship of sleep duration and systolic blood pressure with risk of cardiovascular events using a novel recursive gradient scanning model

Background

Observational studies have suggested U-shaped relationships between sleep duration and systolic blood pressure (SBP) with risks of many cardiovascular diseases (CVDs), but the cut-points that separate high-risk and low-risk groups have not been confirmed. We aimed to examine the U-shaped relationships between sleep duration, SBP, and risks of CVDs and confirm the optimal cut-points for sleep duration and SBP.

Methods

A retrospective analysis was conducted on NHANES 2007-2016 data, which included a nationally representative sample of participants. The maximum equal-odds ratio (OR) method was implemented to obtain optimal cut-points for each continuous independent variable. Then, a novel "recursive gradient scanning method" was introduced for discretizing multiple non-monotonic U-shaped independent variables. Finally, a multivariable logistic regression model was constructed to predict critical risk factors associated with CVDs after adjusting for potential confounders.

Results

A total of 26,691 participants (48.66% were male) were eligible for the current study with an average age of 49.43 ± 17.69 years. After adjusting for covariates, compared with an intermediate range of sleep duration (6.5-8.0 h per day) and SBP (95-120 mmHg), upper or lower values were associated with a higher risk of CVDs [adjusted OR (95% confidence interval) was 1.20 (1.04-1.40) for sleep duration and 1.17 (1.01-1.36) for SBP].

Conclusions

This study indicates U-shaped relationships between SBP, sleep duration, and risks of CVDs. Both short and long duration of sleep/higher and lower BP are predictors of cardiovascular outcomes. Estimated total sleep duration of 6.5-8.0 h per day/SBP of 95-120 mmHg is associated with lower risk of CVDs.

Sleep Deficiency and Cardiometabolic Disease

Epidemiologic studies have demonstrated that short sleep duration is associated with an increased risk of cardio-metabolic health outcomes including cardiovascular disease mortality, coronary heart disease, type 2 diabetes mellitus, hypertension, and metabolic syndrome. Experimental sleep restriction studies have sought to explain these findings. This review describes the main evidence of these associations and possible mechanisms explaining them. Whether sleep extension reverses these now widely acknowledged adverse health effects and the feasibility of implementing such strategies on a public health level is discussed.

Efficacy of sleep extension therapy using a remote support system in university students with increased social jetlag: a parallel, single-blind, randomized controlled trial

Purpose

The efficacy of sleep extension therapy using a remote support system (SET-R) was investigated in university students with increased social jetlag (SJL).

Methods

For this two-arm parallel randomized controlled trial, we recruited Japanese university students with SJL ≥ 60 min. The SET-R provided an individualized sleep schedule for gradual sleep extension using email and sleep hygiene education, stimulus control therapy, and progressive muscle relaxation as web content. The control group was sent an email that encouraged them to record their sleep. The duration of the intervention program was two weeks. The primary outcome was the mean change in SJL two weeks later, assessed using the Munich ChronoType Questionnaire (MCTQ). The other outcomes included Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale (ESS), Insomnia Severity Index, Patient Health Questionnaire-9 (PHQ-9), and sleep quiz. A follow-up survey was conducted 6 months after the intervention.

Results

Of 54 students, 26 were assigned to an intervention group and 28 to a control group. The difference in the mean change in SJL between the two groups (n = 26, n = 27) at two weeks was statistically significant (27.7 min, P = 0.048). The scores for the ESS, PHQ-9, and sleep quiz were improved in the intervention group relative to the control group. At the 6-month follow-up point, the difference in the mean change in SJL between the two groups (n = 22, n = 27) was not statistically significant, but scores for the PHQ-9, and sleep quiz remained significant.

Conclusions

This study demonstrated the efficacy of the SET-R among university students with increased SJL.

Trial Registration

The study was registered with the UMIN Clinical Trials Registry (UMIN000042634, 2021/02/01).

Acute beetroot juice reduces blood pressure in young Black and White males but not females

A complex interplay of social, lifestyle, and physiological factors contribute to Black Americans having the highest blood pressure (BP) in America. One potential contributor to Black adult's higher BP may be reduced nitric oxide (NO) bioavailability. Therefore, we sought to determine whether augmenting NO bioavailability with acute beetroot juice (BRJ) supplementation would reduce resting BP and cardiovascular reactivity in Black and White adults, but to a greater extent in Black adults. A total of 18 Black and 20 White (∼equal split by biological sex) young adults completed this randomized, placebo-controlled (nitrate (NO3-)-depleted BRJ), crossover design study. We measured heart rate, brachial and central BP, and arterial stiffness (via pulse wave velocity) at rest, during handgrip exercise, and during post-exercise circulatory occlusion. Compared with White adults, Black adults exhibited higher pre-supplementation resting brachial and central BP (Ps ≤0.035; e.g., brachial systolic BP: 116(11) vs. 121(7) mmHg, P = 0.023). Compared with placebo, BRJ (∼12.8 mmol NO3-) reduced resting brachial systolic BP similarly in Black (Δ-4±10 mmHg) and White (Δ-4±7 mmHg) adults (P = 0.029). However, BRJ supplementation reduced BP in males (Ps ≤ 0.020) but not females (Ps ≥ 0.299). Irrespective of race or sex, increases in plasma NO3- were associated with reduced brachial systolic BP (ρ = -0.237, P = 0.042). No other treatment effects were observed for BP or arterial stiffness at rest or during physical stress (i.e., reactivity); Ps ≥ 0.075. Despite young Black adults having higher resting BP, acute BRJ supplementation reduced systolic BP in young Black and White adults by a similar magnitude, an effect that was driven by males.

Interventions to increase sleep duration in young people: A systematic review

This systematic review explored the outcomes of current interventions to increase sleep duration in healthy young people (14-25 years). Nine databases were systematically searched, and 26 studies were included in this review. Quality assessment of the included studies was evaluated using two tools: the Newcastle-Ottawa scale, and Cochrane Risk of Bias. The interventions incorporated a range of strategies including behavioral (46.2%), educational (26.9%), a combination of behavioral and educational (15.4%), and other strategies such as physical therapy (11.5%). The findings indicate that behavioral and combination interventions were consistently effective in increasing sleep duration in healthy young people. Educational interventions alone were less effective at increasing young people's sleep duration. Of all the included studies, only one randomized control trial but none of the non-randomized trials were rated as good quality. Our findings suggest a combination of strategies with an emphasis on personalization of intervention could possibly maximize the chances of success at improving sleep duration in healthy young people. More high-quality studies with long-term assessments (≥ 6 months) should be conducted to test the efficacy and durability of interventions to increase sleep duration in young people, as well as the clinical implications to mental and physical health.

The impact of fear of hypoglycaemia on sleep in adolescents with type 1 diabetes

AIMS

Fear of hypoglycaemia (FOH) can contribute to impaired sleep for adults with type 1 diabetes (T1D) and parents of children with T1D, although it is unknown how FOH may affect sleep for adolescents with T1D. This study examines the relationship between adolescent FOH and sleep and assessed the influences of continuous glucose monitor (CGM) and insulin pump use.

METHODS

Adolescents ages 14-18 years with T1D completed questionnaires evaluating FOH (Child Hypoglycemia Fear Survey) and sleep (Pittsburgh Sleep Quality Index, PSQI). Analyses included linear and logistic regression, t-tests and Fisher's exact tests.

RESULTS

Participants included 95 adolescents (52 female) with a median (IQR) age of 16.5 (15.3-17.7) years and a T1D duration of 5.7 (2.5-9.6) years. Analyses showed increased FOH-Worry subscale scores were associated with reduced sleep duration (β = -0.03, p = 0.042, adjusting for BMI z-score, race and ethnicity) and increased sleep disturbances (OR = 1.1, p = 0.038, adjusting for race and ethnicity). Frequent CGM users had longer sleep duration (average 7.5 h) compared with infrequent or non-CGM users (average = 6.8 h; p = 0.029), and pump users had overall improved sleep health as determined by PSQI score (p = 0.019). Technology use did not have significant interactions in the relationships between FOH and sleep duration or sleep disturbances.

CONCLUSIONS

Worrying about hypoglycaemia was associated with impaired sleep for adolescents with T1D. Diabetes technology users have some sleep improvements, but CGM and pump use do little to alter the relationship between FOH and sleep outcomes.

Sleep and Circadian Disturbance in Cardiovascular Risk

PURPOSE OF REVIEW

We discuss the relationship between sleep and circadian factors with cardiovascular disease (CVD) risk, including physiologic, behavioral, and psychological mechanisms along this pathway.

RECENT FINDINGS

The relationship between short and long sleep duration, as well as insomnia, with CVD risk is well-established. Recent work has highlighted how other sleep factors, such as sleep regularity (i.e., consistency of sleep timing), multidimensional sleep health, and circadian factors like chronotype and social jetlag, relate to CVD risk. Sleep-focused interventions (e.g., cognitive behavioral therapy for insomnia and sleep extension) may be effective to reduce CVD risk and disease burden. Sleep is increasingly recognized as an integral component of cardiovascular health. This was underscored by the recent inclusion of sleep duration as a health behavior in the American Heart Association's Life's Essential 8 for defining optimal cardiovascular health.

The impact of sleep–wake problems on health-related quality of life among Japanese nursing college students: a cross sectional survey

Aim

This study was conducted to examine the impact of sleep–wake problems on health-related quality of life of Japanese nursing college students. 

Methods

This cross-sectional study was conducted in 2019 on 150 third and fourth-year nursing college students from two locations in Japan. Insomnia severity was assessed using the Insomnia Severity Index (ISI) and health-related quality of life using the SF-8 questionnaire. The total sleep time (TST) was divided into 3 groups: < 6 h, 6–7 h (reference), and ≥ 7 h. The total ISI score was divided into 2 groups: ≥ 8 points and < 8 points (reference). Logistic regression analysis was performed to evaluate sleep–wake problems related to decline in mental health.

Results

The median mental health indicated in the SF-8 questionnaire was divided into two groups, and the factors causing decline in mental health were investigated. The odds ratios (95% confidence interval) for adjusted ISI ≥ 8 and TST on weekdays < 6 h was 6.51 (2.96–14.30) and 3.38 (1.40–8.17), respectively. Mental health status was significantly lower when ISI ≥ 8 and even lower when TST < 6 h.

Conclusion

Insomnia and short sleep duration are associated with decreased mental health status in nursing college students. Many tended to lack sleep on weekdays. Sleep–wake problems identified while in university should be comprehensively dealt with.

Associations between sleep duration and cardiovascular diseases: A meta-review and meta-analysis of observational and Mendelian randomization studies

The associations between sleep duration and cardiovascular diseases (CVDs) have been explored in many observational studies. However, the causality of sleep duration and many CVDs, such as coronary artery disease (CAD), heart failure (HF), and stroke, remains unclear. In this study, we conducted a systematic meta-review and meta-analysis of the results of observational and Mendelian randomization (MR) studies to examine how sleep duration impacts the risk of CVDs. We searched articles published in English and before 10 September 2021 in PubMed, Web of Science, and Embase. The articles were screened independently by two reviewers to minimize potential bias. We combined the meta-analyses of observational studies and 11 MR studies and summarized evidence of the effect of sleep duration on the risk of CAD, HF, stroke, and cardiovascular and all-cause mortality. Results showed that (a) evidence is accumulating that short sleep duration is a causal risk factor for CAD and HF; (b) abundant evidence from observational studies supports that long sleep duration is associated with the risk of CAD, stroke, and mortality, and long sleep duration has no causal associations with stroke and CAD in the MR studies; the causation of long sleep duration and other CVDs should be further studied; and (c) emerging evidence indicates that an increase in hours of sleep is associated with a decreased risk of CAD. Finally, we discussed the underlying pathophysiological mechanisms underlying short sleep duration and CVDs and suggested that increasing sleep duration benefits cardiovascular health.

Beneficial effects of sleep extension on daily emotion in short-sleeping young adults: An experience sampling study

OBJECTIVES

Short sleep duration has been linked to disrupted emotional experiences and poor emotion regulation. Extending sleep opportunity might therefore offer a means to improve emotion functioning. This study used experience sampling to examine the effect of sleep extension on daily emotion experiences and emotion regulation.

PARTICIPANTS

Participants were young adults (n = 72), aged 18-24 years who reported consistently sleeping less than 7 hours in a 24-hour period in the past 2 weeks.

DESIGN AND SETTING

For 14 consecutive days, participants completed experience sampling questions related to sleep, emotion, and emotion regulation via a smartphone application. Procedures were identical for all participants for the first 7 days ("baseline" assessments).

INTERVENTION

From days 8-14, participants were randomly assigned to either a "sleep extension" condition, in which they were instructed to increase their sleep opportunity by 90 minutes or a "sleep as usual" condition.

MEASUREMENTS

Duration and quality of the previous night's sleep were reported each morning and daytime experiences of positive and negative emotion and emotion regulation were measured at pseudorandom timepoints 6 times a day.

RESULTS

Multilevel modeling demonstrated that participants in the sleep extension condition reported significantly longer sleep times and improved sleep quality, as well as higher positive and lower negative daily emotion, compared to those in the sleep as usual condition.

CONCLUSION

A brief experimental paradigm to extend sleep length has the potential to improve sleep quality and to a minor extent mood, among young adults with short sleep.

Sleep duration irregularity is associated with elevated blood pressure in young adults

Sleep irregularity (i.e., highly variable sleep patterns) is an emerging risk factor for cardiometabolic disease. Though irregular sleep patterns are common among young adults, the cardiometabolic health (CMH) repercussions of sleep irregularity in this population are unclear. We examined associations between sleep duration and irregularity with measures of CMH in 44 (24 M/20 F, 23 ± 5y, BMI 26 ± 4 kg/m², blood pressure (BP): 125/71 ± 14/9 mmHg) young adults. Participants wore actigraphy monitors for seven-days and sleep duration irregularity was operationalized as the standard deviation of nightly sleep duration (sleep SD). CMH variables of interest included brachial and aortic BP, arterial stiffness (cf-PWV), augmentation index (AIx75), and fasting blood glucose and lipids. Associations between sleep duration and sleep SD with CMH variables were assessed via correlations adjusted for sex and BMI. Sleep duration generally was not associated with CMH indices. However, sleep SD was associated with brachial systolic (r = 0.433, p = .027) and diastolic BP (r = 0.415, p = .035). Similarly, sleep duration SD was associated with aortic systolic BP (r = 0.447, p = .022). Our findings show that sleep irregularity, but not duration, is associated with higher brachial and central BP in young adults.Abbreviations: AIx75: augmentation index at a heart rate of 75 beats per minute; BP: blood pressure; CMH: cardiometabolic health; cf-PWV: carotid-femoral pulse wave velocity; DXA: dual x-ray absorptiometry; mg/dl: milligrams per deciliter; PWA: pulse wave analysis; PWV: pulse wave velocity; sleep duration SD: standard deviation of nightly sleep duration.

Sleep Deficiency and Cardiometabolic Disease

Epidemiologic studies have demonstrated that short sleep duration is associated with an increased risk of cardio-metabolic health outcomes including cardiovascular disease mortality, coronary heart disease, type 2 diabetes mellitus, hypertension, and metabolic syndrome. Experimental sleep restriction studies have sought to explain these findings. This review describes the main evidence of these associations and possible mechanisms explaining them. Whether sleep extension reverses these now widely acknowledged adverse health effects and the feasibility of implementing such strategies on a public health level is discussed.

The association of salivary alpha-amylase, heart rate variability, and psychological stress on objectively measured sleep behaviors among college students

Objective

This study aimed to evaluate sleep behaviors among college students, to assess salivary alpha-amylase (sAA) and heart rate variability (HRV) in association with stress, and to investigate sleep-related factors including sAA, HRV, and stress among them.

Methods

Saliva samples for sAA assessment and HRV measurements in the supine position were taken between 3 PM and 6 PM. The level of prolonged psychological stress for the previous week was evaluated using the Korean version of the Global Assessment of Recent Stress (GARS-K), and sleep behaviors were assessed using an actigraphy device.

Results

A total of 86 healthy college students participated in this study. Sleep behaviors of the college students were not good, with 84% sleep efficiency (SE) and 62.7 min wake after sleep onset (WASO). The average sAA level was 65.8 U/mL in the participants. Although neither the sAA level nor HRV indices were significantly correlated with prolonged psychological stress, decreased normalized high frequency (nHF) on HRV was independently associated with a higher level of stress when adjusted for age and sex. Higher stress (r = −0.276, P = 0.011) and lower sAA (r = 0.266, P = 0.030) had significant correlations with shorter time in bed; however, it was sAA that was independently associated with time in bed (β = 0.244, p = 0.044). Decreased nHF (β = 0.245, P = 0.027) and higher body mass index (BMI) (β = −0.224, P = 0.043) were independently related to and poorer SE.

Conclusions

Poor sleep behaviors were associated with decreased parasympathetic activity, a physiological change to psychological stress, rather than with psychological stress itself among college students. Thus, sAA and HRV should be considered as significant factors for impaired sleep behaviors in relation to psychological stress.

The validity and reliability study of the Cleveland Adolescent Sleepiness ​Questionnaire and examination of the sleepiness of university students

PURPOSE

This study aimed to determine the reliability and validity of the Cleveland Adolescent Sleepiness Questionnaire in Turkish university students, and to determine the sleepiness of students.

DESIGN AND METHODS

This cross-sectional study was carried out with 852 university students in Turkey, Bolu, between February- May 2019.

FINDINGS

Results of the analysis indicated that this scale was a valid and reliable measurement tool. As the scores of students' get from Cleveland Adolescent Sleepiness Questionnaire increased, the frequency of students feeling sleepy during the day, sleepiness in and out of school, and getting up in the morning without resting increased.

PRACTICE IMPLICATIONS

Nurses can use this scale when evaluating university students' sleepiness.

Effect of five nights of sleep extension on peripheral vascular function: a randomized crossover investigation into long sleep duration

Long sleep duration, defined as ≥9 h, is associated with increased cardiovascular mortality. We sought to determine the effect of sleep extension on peripheral vascular health. Twelve middle-aged adults were randomly assigned to spend five nights with 8 h (control) or 10+ hours time in bed (TIB) in a crossover fashion. Sleep was assessed using wrist actigraphy. Peak reactive hyperemia in the forearm was measured using venous-occlusion plethysmography as an index of microvascular vasodilation. Nighttime and morning blood pressure was recorded along with pulse wave velocity (arterial stiffness). Average sleep duration was 7.1 ± 0.3 and 9.3 ± 0.3 h for 8 and 10+ hours TIB (P < 0.001), respectfully. On average, sleep was extended by 127 ± 29 min with nine participants reaching average sleep durations >9 h. Extended sleep did not change nighttime or morning blood pressure, or pulse wave velocity (all P > 0.05). In contrast, peak forearm vascular conductance (FVC, 0.27 ± 0.08 vs. 0.23 ± 0.07 ml/100 ml/min/mmHg, P = 0.02) and total excess blood flow (28 ± 9 vs. 24 ± 11 ml/100 ml, P < 0.01) were increased following sleep extension. The change in FVC and total excess blood flow were inversely correlated with the change in wake after sleep onset and TIB (both r = -0.62, P < 0.05), but not with sleep duration. These results demonstrate that extended time in bed accompanied by long sleep durations does not impair peripheral vascular function, but rather, may increase microvasculature vasodilatory capacity in midlife adults.

Sleep Duration and Hypertension: Epidemiological Evidence and Underlying Mechanisms

While the contribution of several physiological systems to arterial blood pressure regulation has been studied extensively, the role of normal and disrupted sleep as a modifiable determinant of blood pressure control, and in the pathophysiology of hypertension, has only recently emerged. Several sleep disorders, including sleep apnea and insomnia, are thought to contribute to the development of hypertension, although less attention is paid to the relationship between sleep duration and blood pressure independent of sleep disorders per se. Accordingly, this review focuses principally on the physiology of sleep and the consequences of abnormal sleep duration both experimentally and at the population level. Clinical implications for patients with insomnia who may or may not have abbreviated sleep duration are explored. As a corollary, we further review studies of the effects of sleep extension on blood pressure regulation. We also discuss epidemiological evidence suggesting that long sleep may also be associated with hypertension and describe the parabolic relationship between total sleep time and blood pressure. We conclude by highlighting gaps in the literature regarding the potential role of gut microbial health in the cross-communication of lifestyle patterns (exercise, diet, and sleep) with blood pressure regulation. Additionally, we discuss populations at increased risk of short sleep, and specifically the need to understand mechanisms and therapeutic opportunities in women, pregnancy, the elderly, and in African Americans.

Behavioral interventions to extend sleep duration: A systematic review and meta-analysis

The goal of this study was to examine the effects of behavioral sleep extension interventions on sleep duration outcomes in children and adults ≥ age 12. We conducted a systematic literature review, article extraction and meta-analysis. Our search yielded 42 studies from 14 countries. The majority of studies (n = 19) enrolled adults, 10 studies enrolled college students, 13 enrolled children (high school or middle school aged). Results from the meta-analysis demonstrated behavioral sleep extension resulted in a significantly higher sleep duration as compared to control group or baseline, with pooled standardized mean difference (SMD) that was similar for both two-arm 0.80 (95 % CI 0.28 to 1.31; p < 0.01; I2 = 99.2%) and one-arm studies 0.75 (95% CI 0.39 to 1.11; p < 0.01; I2 = 86%), and there was significant heterogeneity among both study types. Subgroup analyses revealed that studies with direct interventions on sleep duration (i.e., specified the sleep schedule) had larger effects compared to indirect methods (coaching, educational approaches) and a greater number of curriculum components was associated with smaller effects. Results of this review demonstrate that sleep extension studies are effective at extending sleep in a variety of populations but improving the description of intervention methods and use of more rigorous study designs will improve the quality and reproducibility of this area of research.

Association between Stress and Metabolic Syndrome and its Mediating Factors in University Students

OBJECTIVES

In this study, we evaluated the association between perceived stress and indicators of metabolic syndrome and how this association is mediated by sleep problems, unhealthy eating habits, and night eating syndrome, in addition to serum levels of ghrelin and cortisol in university students.

METHODS

We recruited 192 students from a public university in Mexico. Weight, height, waist circumference and blood pressure were taken in accordance with standard protocols. Validated questionnaires were used to assess perceived stress, sleep quality and eating habits. Fasting blood samples were taken to measure ghrelin, cortisol, triglycerides, glucose and HDL-C.

RESULTS

Path Analysis indicated direct positive effects of stress over PSQI (β = 0.341) and NES (β = 0.443); PSQI over NES (β = 0.233) and NES over glucose (β = 0.170), triglycerides over LDL-C (β = 0.215), waist circumference over SBP (β = 0.259). Likewise, standardized negative regression weights of PSQI over Diet Quality Index (β = -0.239) and ghrelin concentrations (β = -0.132), ghrelin over Diet Quality Index (β = -0.188) and waist circumference (β = -0.147). Diet Quality Index over triglycerides (β = -0.184); sleep duration over systolic blood pressure (β = -0.242); waist circumference over HDL-C (β = -0.256).

CONCLUSION

Psychological stress leads to increased indicators of MetS via decreased sleep quality, inadequate eating habits and eating behavior in university students.

Sleep is essential to health: an American Academy of Sleep Medicine position statement

CITATION

Sleep is a biological necessity, and insufficient sleep and untreated sleep disorders are detrimental for health, well-being, and public safety. Healthy People 2030 includes several sleep-related objectives with the goal to improve health, productivity, well-being, quality of life, and safety by helping people get enough sleep. In addition to adequate sleep duration, healthy sleep requires good quality, appropriate timing, regularity, and the absence of sleep disorders. It is the position of the American Academy of Sleep Medicine (AASM) that sleep is essential to health. There is a significant need for greater emphasis on sleep health in education, clinical practice, inpatient and long-term care, public health promotion, and the workplace. More sleep and circadian research is needed to further elucidate the importance of sleep for public health and the contributions of insufficient sleep to health disparities.

CITATION

Ramar K, Malhotra RK, Carden KA, et al. Sleep is essential to health: an American Academy of Sleep Medicine position statement. J Clin Sleep Med. 2021;17(10):2115-2119.

Sleep Patterns and Their Association with Blood Pressure and Heart Rate Variability Parameters in Young Saudi Females

Objectives

Disturbed sleep patterns might alter the autonomic tone and lead to various cardiovascular morbidities. This study aimed to determine sleep patterns (quality, duration, efficiency and daytime sleepiness) and explore their association with blood pressure (BP) and heart rate variability (HRV) in apparently healthy, young Saudi females.

Methods

This cross-sectional study was conducted in the Department of Physiology, Imam Abdulrahman Bin Faisal University, Saudi Arabia between March 2019 and December 2019. Self-reported Pittsburgh Sleep Quality Index and Epworth Sleepiness Scale questionnaires were used to collect data. In addition, the participants’ BP and HRV was measured. Based on the cut-off values of sleep quality, duration, efficiency and daytime sleepiness scores, participants were categorised into groups. HRV and BP were compared between the groups by a t-test/one-way ANOVA.

Results

A total of 98 participants were included in this study (response rate: 72.6%). Poor sleep patterns (quality, duration and efficiency) were observed, but no association was found with BP and HRV parameters among groups with different sleep quality, duration and efficiency. Systolic BP was significantly increased in the moderate to severe daytime sleepiness group (P = 0.039). Dozing off as a passenger in a car, in the afternoon and after lunch were negatively correlated with HRV parameters (P <0.05).

Conclusion

Sleep quality, duration and efficiency were not found to be statistically significant, but various dozing-off situations were associated with fluctuations in HRV parameters. Daytime sleepiness may augment sympathetic responses in apparently healthy female participants.

Changes in health promoting behavior during COVID-19 physical distancing: Utilizing wearable technology to examine trends in sleep, activity, and cardiovascular indicators of health

The COVID-19 pandemic incited unprecedented restrictions on the behavior of society. The aims of this study were to quantify changes to sleep/wake behavior and exercise behavior, as well as changes in physiological markers of health during COVID-19 physical distancing. A retrospective analysis of 5,436 US-based subscribers to the WHOOP platform (mean age = 40.25 ± 11.33; 1,536 females, 3,900 males) was conducted covering the period from January 1st, 2020 through May 15th, 2020. This time period was separated into a 68-day baseline period and a 67-day physical distancing period. To provide context and allow for potential confounders (e.g., change of season), data were also extracted from the corresponding time periods in 2019. As compared to baseline, during physical distancing, all subjects fell asleep earlier (-0.15 hours), woke up later (0.29 hours), obtained more sleep (+0.21 hours) and reduced social jet lag (-0.13 hours). Contrasting sleep behavior was seen in 2019, with subjects falling asleep and waking up at a similar time (-0.01 hours; -0.03 hours), obtaining less sleep (-0.14 hours) and maintaining social jet lag (+0.06 hours) in corresponding periods. Individuals exercised more intensely during physical distancing by increasing the time spent in high heart rate zones. In 2020, resting heart rate decreased (-0.90 beats per minute) and heart rate variability increased (+0.98 milliseconds) during physical distancing when compared to baseline. However, similar changes were seen in 2019 for RHR (-0.51 beats per minute) and HRV (+2.97 milliseconds), suggesting the variation may not be related to the introduction of physical distancing mandates. The findings suggest that individuals improved health related behavior (i.e., increased exercise intensity and longer sleep duration) during physical distancing restrictions. While positive changes were seen to cardiovascular indicators of health, it is unclear whether these changes were a direct consequence of behavior change.

Naturally Occurring Consecutive Sleep Loss and Day-to-Day Trajectories of Affective and Physical Well-Being

BACKGROUND

Experimental studies have shown that just 1 night of sleep loss impairs next-day performance, mood, and energy. Yet, little is known about the effects of consecutive sleep loss on daily well-being in participants' own settings.

PURPOSE

This study examined whether and how naturally occurring consecutive sleep loss is associated with day-to-day trajectories of affective and physical well-being.

METHODS

Participants were adults (N = 1,958) from the Midlife in the United States Study who provided daily diary data for eight consecutive days. Consecutive sleep loss was operationalized as the within-person number of consecutive nights with <6 hr of sleep. Multilevel models evaluated the linear, quadratic, and cubic effects of consecutive sleep loss on daily well-being, after controlling for sociodemographic, health, and daily covariates.

RESULTS

Daily negative affect increased and positive affect decreased in curvilinear fashion as the number of consecutive sleep loss increased. For example, daily negative affect increased (linear), but the rate of increase decelerated as the number of consecutive sleep loss increased (quadratic). Results were consistent for the number and severity of physical symptoms. For negative affect and the severity of physical symptoms, cubic effect was also significant such that the rate of increase accelerated again in the days most distal to baseline (no sleep loss).

CONCLUSIONS

Consecutive sleep loss was associated with degraded trajectories of daily affective and physical well-being. Making efforts to break the vicious cycle of sleep loss may protect daily well-being in adults whose sleep time is often compromised.

Causal associations of short and long sleep durations with 12 cardiovascular diseases: linear and nonlinear Mendelian randomization analyses in UK Biobank

AIMS

Observational studies have suggested strong associations between sleep duration and many cardiovascular diseases (CVDs), but causal inferences have not been confirmed. We aimed to determine the causal associations between genetically predicted sleep duration and 12 CVDs using both linear and nonlinear Mendelian randomization (MR) designs.

METHODS AND RESULTS

Genetic variants associated with continuous, short (≤6 h) and long (≥9 h) sleep durations were used to examine the causal associations with 12 CVDs among 404 044 UK Biobank participants of White British ancestry. Linear MR analyses showed that genetically predicted sleep duration was negatively associated with arterial hypertension, atrial fibrillation, pulmonary embolism, and chronic ischaemic heart disease after correcting for multiple tests (P < 0.001). Nonlinear MR analyses demonstrated nonlinearity (L-shaped associations) between genetically predicted sleep duration and four CVDs, including arterial hypertension, chronic ischaemic heart disease, coronary artery disease, and myocardial infarction. Complementary analyses provided confirmative evidence of the adverse effects of genetically predicted short sleep duration on the risks of 5 out of the 12 CVDs, including arterial hypertension, pulmonary embolism, coronary artery disease, myocardial infarction, and chronic ischaemic heart disease (P < 0.001), and suggestive evidence for atrial fibrillation (P < 0.05). However, genetically predicted long sleep duration was not associated with any CVD.

CONCLUSION

This study suggests that genetically predicted short sleep duration is a potential causal risk factor of several CVDs, while genetically predicted long sleep duration is unlikely to be a causal risk factor for most CVDs.

Sleep and chronotype in relation to work-related stress and negative affect: The moderating role of a flexible start of work

Objectives

The present study investigated the relationships between sleep (sleep duration and need for additional sleep time in the morning), chronotype, work-related stress, and negative affect in daytime workers. Furthermore, it was examined whether a flexible start of work moderates these relationships.

Methods

A cross-sectional online study was conducted. Participants were 438 (247 female) daytime workers between 18 and 73 years (mean = 37.68, standard deviation = 12.39). The questionnaire included the “sleep duration” subscale of the Pittsburgh Sleep Quality Index (PSQI), the Morningness–Eveningness Questionnaire (MEQ), two subscales of the Trier Inventory for the Assessment of Chronic Stress (TICS), the negative affect scale of the Positive and Negative Affect Schedule (PANAS), questions regarding how many minutes participants would like to sleep longer in the morning, and how flexible their start of work is.

Results

Short sleep duration and a greater need for additional sleep in the morning were significantly associated with late chronotype. Shorter sleep duration, a greater need for additional sleep, and a late chronotype were associated with higher work-related stress and negative affect. A flexible start of work moderated these relationships: People with longer sleep duration, less need for additional sleep time, and an early chronotype showed lower stress and negative affect levels when having a flexible start of work. A flexible start of work showed no or negative effects on workers with shorter sleep duration, a greater need for additional sleep time, or a late chronotype.

Conclusions

The effect of a flexible start of work for daytime worker’s well-being depends on a person’s individual sleep timing and chronotype.

The feasibility of at-home sleep extension in adolescents and young adults: A meta-analysis and systematic review

Insufficient sleep duration is detrimental to health and performance and is alarmingly common in adolescents and young adults. The aim of this pre-registered meta-analysis was to determine the feasibility of at-home sleep extension as a means to improve sleep duration and daytime sleepiness, and maintain or improve sleep quality and efficiency, in adolescents and young adults. Peer-reviewed journal articles and dissertations were screened to identify studies with at least five consecutive days of at-home sleep extension, pre- and post-extension measurement of sleep duration, and participants 13-30 years of age. Out of 2254 studies assessed for eligibility, 17 met review inclusion criteria - seven in adolescents and ten in young adults. At-home extension of sleep opportunity reliably increased sleep duration and sleep quality, and decreased daytime sleepiness when compared to unmanipulated sleep opportunity. These results indicate that at-home sleep extension is feasible in adolescents and young adults. However, the degree of improvement in sleep duration, sleep quality, and daytime sleepiness varied by study population and sleep extension method, which will have downstream consequences for the effectiveness of sleep extension as an experimental manipulation and intervention to improve health and performance during adolescence and young adulthood.

Sleep Extension: A Potential Target for Obesity Treatment

PURPOSE OF REVIEW

Sleep and obesity share a bidirectional relationship, and weight loss has been shown to enhance sleep. Aiming to extend sleep on its own or as part of a lifestyle intervention may attenuate health consequences of short sleep. This review highlights several sleep extension approaches, discusses feasibility of each, and summarizes findings relevant to obesity.

RECENT FINDINGS

Sleep extension in response to experimental sleep restriction demonstrates partial rescue of cardiometabolic dysfunction in some but not all studies. Adequate sleep on a nightly basis may be necessary for optimal health. While initial sleep extension interventions in habitually short sleepers have been met with obstacles, preliminary findings suggest that sleep extension or sleep hygiene interventions may improve glycemic control, decrease blood pressure, and enhance weight loss. Sleep extension has the potential to attenuate obesity risk and cardiometabolic dysfunction. There is tremendous opportunity for future research that establishes a minimum threshold for sleep extension effectiveness and addresses logistical barriers identified in seminal studies.