Partial Sleep Deprivation Reduces the Efficacy of Orexin-A to Stimulate Physical Activity and Energy Expenditure

Baseline prepulse inhibition dependency of orexin A and REM sleep deprivation

RATIONALE

Prepulse inhibition (PPI) impairment reflects sensorimotor gating problems, i.e. in schizophrenia. This study aims to enlighten the role of orexinergic regulation on PPI in a psychosis-like model.

OBJECTIVES

In order to understand the impact of orexinergic innervation on PPI and how it is modulated by age and baseline PPI (bPPI), chronic orexin A (OXA) injections was carried on non-sleep-deprived and sleep-deprived rats that are grouped by their bPPI.

METHODS

bPPI measurements were carried on male Wistar rats on P45 or P90 followed by grouping into low-PPI and high-PPI rats. The rats were injected with OXA twice per day for four consecutive days starting on P49 or P94, while the control groups received saline injections. 72 h REMSD was carried on via modified multiple platform technique on P94 and either OXA or saline was injected during REMSD. PPI tests were carried out 30 min. after the last injection.

RESULTS

Our previous study with acute OXA injection after REMSD without bPPI grouping revealed that low OXA doses might improve REMSD-induced PPI impairment. Our current results present three important conclusions: (1) The effect of OXA on PPI is bPPI-dependent and age-dependent. (2) The effect of REMSD is bPPI-dependent. (3) The effect of OXA on PPI after REMSD also depends on bPPI.

CONCLUSION

Orexinergic regulation of PPI response with and without REMSD can be predicted by bPPI levels. Our findings provide potential insights into the regulation of sensorimotor gating by sleep/wakefulness systems and present potential therapeutic targets for the disorders, where PPI is disturbed.

Behavioral phenotyping based on physical inactivity can predict sleep in female rats before, during, and after sleep disruption

BACKGROUND

A noninvasive method that can accurately quantify sleep before, during, and after sleep disruption (SD) has not been validated in female rats across their estrous cycle. In female rats, we hypothesized that the duration of physical inactivity (PIA) required to predict sleep would 1) change with the differences in baseline sleep between the circadian and estrous cycle phases and 2) predict sleep and the change in sleep (Δsleep) before, during, and after SD independent of circadian and estrous cycle phase.

NEW METHODS

EEG, EMG, physical activity and estrous cycle phase were measured in female Sprague-Dawley rats before, during, and after SD. Sleep was determined by two methods [EEG/EMG and a duration of continuous PIA (i.e., PIA criterion)]. Reliability between the methods was tested with a previously validated criterion (40 s). Sensitivity analyses and criterion-related validity analyses for sleep during SD and recovery were conducted across multiple PIA criteria (10 s-120 s). Predictability between the two methods and Δsleep was calculated.

RESULTS/COMPARISON WITH EXISTING METHODS

Three criteria (10 s, 20 s, 30 s) predicted baseline sleep independent of circadian and estrous cycle phase. Sleep during SD and recovery were predicted by two criteria (30 s and 10 s). Δsleep between study periods was not reliably predicted by a single PIA criterion.

CONCLUSION

PIA predicted sleep independent of estrous cycle phase in female rats. However, the specific criterion was dependent upon the study period (before, during, and after SD) and circadian phase. Thus, prior work validating a PIA criterion in male rodents is not applicable to the female rat.

Sleep and cardiometabolic risk. Narrative revision

OBJECTIVES

Sleep disturbances, including disrupted sleep and short sleep duration, are highly prevalent and are prospectively associated with an increased risk for various chronic diseases, including cardiometabolic, neurodegenerative, and autoimmune diseases.

MATERIAL AND METHODS

This is a narrative review of the literature based on numerous articles published in peer-reviewed journals since the beginning of this century.

RESULTS

The relationship between sleep disorders and metabolic dysregulation has been clearly established, mainly in the setting of modern epidemic of cardiometabolic disease, a cluster of conditions include obesity, insulin resistance, arterial hypertension, and dyslipidaemia, all of them considered as main risk factor for atherosclerotic cardiovascular disease (ACVD) and its clinical expression such as ischemic ictus, myocardial infarction and type 2 diabetes. Clinically viable tools to measure sleep duration and quality are needed for routine screening and intervention.

CONCLUSIONS

In view of what has been exposed in this review, it is evident that the timing, amount, and quality of sleep are critical to reduce the burden of risk factors for several chronic disease, including ACVD and type 2 diabetes, and most relevant in young people. Future research studies should elucidate the effectiveness of multimodal interventions to counteract the risk of short sleep for optimal patient outcomes across the healthcare continuum, especially in young people.

The prevalence and associated factors of sleep deprivation among healthy college students in China: a cross-sectional survey

Background

The prevalence of sleep deprivation among college students is increasing and has a few associated factors.

Methods

The present study analyzed 2,142 college students from 28 provinces in China. The Chinese version of the Pittsburgh Sleep Quality Index (PSQI) was used to assess sleep duration. Binary logistic regression was conducted to explore the sleep deprivation related factors. Age and gender were controlled as covariates.

Results

Among the 2,142 college students (27.7% male, 72.3% female), 1,620 (75.6%) reported the average sleep duration was below 7 h per day for one month, 49.3% (1,055/2,142) slept 6∼7 h (contains 6 h), 21.0% (449/2,142) slept 5∼6 h (contains 5 h), and 5.4% (116/2,142) slept <5 h. Age increased the risk of sleep deprivation, the adjusted odds ratio = 1.05 (95% CI [1.01∼1.10]). The adjusted odds ratio (A-OR) for sleep deprivation was higher for students of more than 60 min nap duration per day (A-OR = 2.35, 95% CI [1.45∼3.80]), and age growth (A-OR = 1.05, 95% CI [1.01∼1.10]). In contrast, A-ORs were lower among sleeping inconsistency between work and rest days (A-OR = 0.61, 95% CI [0.49∼0.75]), accustomed to staying up late (A-OR = 0.45, 95% CI [0.36∼0.57]), staying up late to work or study (A-OR = 0.62, 95% CI [0.49∼0.78]), stress (A-OR = 0.75, 95% CI [0.58∼0.98]), and repeated thoughts in bed had (A-OR = 0.79, 95% CI [0.62∼0.99]).

Conclusions

Sleep deprivation is extremely common among healthy college students in China. It is necessary to perform methods maintaining enough sleep due to the current high incidence of sleep deprivation. Controlling the nap duration and getting enough sleep on rest days to replace missing hours of sleep on workdays might improve college students' sleep.

Associations Between Sleep and Metabolic Outcomes in Preadolescent Children

Context

Growing evidence suggests an important role for sleep for the metabolic health of children.

Objective

We aimed to determine how sleep is related to insulin sensitivity, insulin secretion, beta-cell function, and adiposity (BMI z-scores, body fat %, waist to height ratio) using objectively measured sleep and oral glucose tolerance test (OGTT)-derived measures.

Methods

Sixty-two children aged 7-11 years, born at Kaiser Permanente Southern California, wore wrist accelerometers for 7 days to objectively measure sleep, completed an OGTT, and had anthropometric measures (height [cm], weight [kg], waist [cm], body fat [%]) collected. Using linear regression, associations between Matsuda insulin sensitivity index (ISI), insulinogenic index (IGI), disposition index (DI), BMI z-score, waist to height ratio, and body fat % with sleep parameters [total sleep time (TST; min), sleep efficiency (SE; %), time in bed (TIB; min), wake after sleep onset (WASO; min), and sleep latency (SL; min)] were assessed. Body fat % was tested as a mediator of the relationship between TST and ISI.

Results

Longer TST was associated with better insulin sensitivity (P = 0.02), but not after adjusting for body fat %. Sleep parameters were not associated with IGI or DI. Longer TST was associated with lower % body fat (P = 0.01) and lower waist-to-height-ratios (P = 0.05). Body fat % explained 62% (P = 0.01) of the relationship between TST and ISI. Longer TIB was associated with lower adiposity measures (P < 0.05). There were no associations between SE, WASO, or SL and metabolic outcomes.

Conclusion

Objectively measured sleep duration was associated with lower adiposity, and the relationship between sleep duration and ISI appeared partly through adiposity levels in preadolescent children. Longer sleep duration may be important for metabolic health.

Orexin, serotonin, and energy balance

The lateral hypothalamus is critical for the control of ingestive behavior and spontaneous physical activity (SPA), as lesion or stimulation of this region alters these behaviors. Evidence points to lateral hypothalamic orexin neurons as modulators of feeding and SPA. These neurons affect a broad range of systems, and project to multiple brain regions such as the dorsal raphe nucleus, which contains serotoninergic neurons (DRN) important to energy homeostasis. Physical activity is comprised of intentional exercise and SPA. These are opposite ends of a continuum of physical activity intensity and structure. Non‐goal‐oriented behaviors, such as fidgeting, standing, and ambulating, constitute SPA in humans, and reflect a propensity for activity separate from intentional activity, such as high‐intensity voluntary exercise. In animals, SPA is activity not influenced by rewards such as food or a running wheel. Spontaneous physical activity in humans and animals burns calories and could theoretically be manipulated pharmacologically to expend calories and protect against obesity. The DRN neurons receive orexin inputs, and project heavily onto cortical and subcortical areas involved in movement, feeding and energy expenditure (EE). This review discusses the function of hypothalamic orexin in energy‐homeostasis, the interaction with DRN serotonin neurons, and the role of this orexin‐serotonin axis in regulating food intake, SPA, and EE. In addition, we discuss possible brain areas involved in orexin–serotonin cross‐talk; the role of serotonin receptors, transporters and uptake‐inhibitors in the pathogenesis and treatment of obesity; animal models of obesity with impaired serotonin‐function; single‐nucleotide polymorphisms in the serotonin system and obesity; and future directions in the orexin–serotonin field.

This article is categorized under:

Metabolic Diseases > Molecular and Cellular Physiology

Assessment of sleep and obesity in adults and children: Observational study

The sleep allows many psychological processes, such as immune system activity, body metabolism and hormonal balance, emotional and mental health, learning, mnemonic processes. The lack of sleep could undermine mental and physical purposes, causing an alteration in cognitive functions or metabolic disorders. In our study, we have examined the irregular sleep effects with the overweight and obesity risk in children and adults.The sample was composed of 199 subjects, of which 71 adults, (29 males and 42 females), and 128 children (73 males and 55 females). We have measured the weight and height with standard techniques; we also have measured the body mass index dividing the weight in kg with the height square expressed in meters (kg/m). Subjects were divided into underweight, normal weight, overweight, and obese. Were administered some questionnaires to measure the quantity and quality of sleep, and eating habits and individual consumption of food.Analysis of demographic variables not showed significant differences between male and female groups but highlighted a significant trend differences in normal-weight score. The clinical condition has a substantial impact on body mass index score and sleep hours were significant predictor on this.Quantity and quality sleep can also represent a risk factor of overweight and obesity, so sufficient sleep is a factor that influence a normal weight. Adults and children that sleep less, have an increase in obesity and overweight risk with dysfunctional eating behaviors, decreased physical activity, and metabolic changes.

Associations of Various Nighttime Noise Exposure Indicators with Objective Sleep Efficiency and Self-Reported Sleep Quality: A Field Study

It is unclear which noise exposure time window and noise characteristics during nighttime are most detrimental for sleep quality in real-life settings. We conducted a field study with 105 volunteers wearing a wrist actimeter to record their sleep during seven days, together with concurrent outdoor noise measurements at their bedroom window. Actimetry-recorded sleep latency increased by 5.6 min (95% confidence interval (CI): 1.6 to 9.6 min) per 10 dB(A) increase in noise exposure during the first hour after bedtime. Actimetry-assessed sleep efficiency was significantly reduced by 2%-3% per 10 dB(A) increase in measured outdoor noise (Leq, 1h) for the last three hours of sleep. For self-reported sleepiness, noise exposure during the last hour prior to wake-up was most crucial, with an increase in the sleepiness score of 0.31 units (95% CI: 0.08 to 0.54) per 10 dB(A) Leq,1h. Associations for estimated indoor noise were not more pronounced than for outdoor noise. Taking noise events into consideration in addition to equivalent sound pressure levels (Leq) only marginally improved the statistical models. Our study provides evidence that matching the nighttime noise exposure time window to the individual's diurnal sleep-wake pattern results in a better estimate of detrimental nighttime noise effects on sleep. We found that noise exposure at the beginning and the end of the sleep is most crucial for sleep quality.

Noise-induced sleep disruption increases weight gain and decreases energy metabolism in female rats

Background/objectives:

Inadequate sleep increases obesity and environmental noise contributes to poor sleep. However, women may be more vulnerable to noise and hence more susceptible to sleep disruption-induced weight gain than men. In male rats, exposure to environmental (i.e. ambient) noise disrupts sleep and increases feeding and weight gain. However, the effects of environmental noise on sleep and weight gain in female rats are unknown. Thus, this study was designed to determine whether noise exposure would disturb sleep, increase feeding and weight gain and alter the length of the estrous cycle in female rats.

Subjects/methods:

Female rats (12-weeks old) were exposed to noise for 17d (8h/d during the light period) to determine the effects of noise on weight gain and food intake. In a separate set of females, estrous cycle phase and length, EEG, EMG, spontaneous physical activity and energy expenditure were recorded continuously for 27d during baseline (control, 9d), noise exposure (8h/d, 9d) and recovery (9d) from sleep disruption.

Results:

Noise exposure significantly increased weight gain and food intake compared to females that slept undisturbed. Noise also significantly increased wakefulness, reduced sleep and resulted in rebound sleep during the recovery period. Total energy expenditure was significantly lower during both noise exposure and recovery due to lower energy expenditure during spontaneous physical activity and sleep. Notably, noise did not alter the estrous cycle length.

Conclusions:

As previously observed in male rats, noise exposure disrupted sleep and increased weight gain in females but did not alter the length of the estrous cycle. This is the first demonstration of weight gain in female rats during sleep disruption. We conclude that the sleep disruption caused by exposure to environmental noise is a significant tool for determining how sleep loss contributes to obesity in females.

Role of Sex and the Environment in Moderating Weight Gain Due to Inadequate Sleep

PURPOSE OF REVIEW

The growing prevalence of obesity, inadequate sleep and sleep disorders together with the negative impact of lack of sleep on overall health highlights the need for therapies targeted towards weight gain due to sleep loss.

RECENT FINDINGS

Sex disparities in obesity and sleep disorders are present; yet, the role of sex is inadequately addressed and thus it is unclear whether sensitivity to sleep disruption differs between men and women. Like sex, environmental factors contribute to the development of obesity and poor sleep. The obesogenic environment is characterized by easy access to palatable foods and a low demand for energy expenditure in daily activities. These and other environmental factors are discussed, as they drive altered sleep or their interaction with food choice and intake can promote obesity. We discuss data that suggest differences in sleep patterns and responses to sleep disruption influence sex disparities in weight gain, and that enviromental disturbances alter sleep and interact with features of the obesogenic environment that together promote obesity.