The effects of sleep restriction and altered sleep timing on energy intake and energy expenditure

Short Sleep Duration Disrupts Glucose Metabolism: Can Exercise Turn Back the Clock?

Short sleep duration is prevalent in modern society and may be contributing to type 2 diabetes prevalence. This review will explore the effects of sleep restriction on glycemic control, the mechanisms causing insulin resistance, and whether exercise can offset changes in glycemic control. Chronic sleep restriction may also contribute to a decrease in physical activity leading to further health complications.

Cross-sectional associations of actigraphy-assessed sleep with dietary outcomes in emerging adults

BACKGROUND/OBJECTIVES

Emerging adults (~18-28 years of age) have a high prevalence of poor sleeping habits and poor diet quality; however, little is known on whether these poor sleeping habits are associated with dietary outcomes in this age group. This study assessed associations between actigraphy-based sleep with energy intake (EI), overall diet quality, and measures of meal timing in emerging adults.

SUBJECTS/METHODS

Data on 135 emerging adults (age = 19.4 ± 1.3 years; body mass index (BMI) = 26.5 ± 6.9 kg/m2; 58% female; 65% White) from the RIGHT Track Health project were used. Measures included actigraphy-assessed sleep duration, sleep efficiency, sleep timing midpoint, day-to-day sleep duration and sleep timing midpoint variability and combined sleep duration and sleep timing behaviors (early-bed/late-rise, early-bed/early-rise, late-bed/late-rise, late-bed/early-rise); EI (three 24-h dietary recalls), diet quality (Healthy Eating Index 2015 total score) and meal timing outcomes (timing of first and last meal intake, total duration, and midpoint of the eating window).

RESULTS

Shorter sleep duration, later sleep timing midpoint and greater sleep efficiency, as well as combined late-bed/late-rise and late-bed/early-rise groups, were associated with lower diet quality. Greater sleep timing midpoint variability was associated with higher EI, and the late-bed/early-rise group had significantly delayed first meal timing.

CONCLUSION

In emerging adults, shorter sleep duration and later sleep timing are associated with lower overall diet quality, and greater sleep timing variability is associated with higher EI. Future research is needed to examine the role of sleep on diet quality and eating habits to identify potential targets for nutritional interventions in this age group.

Sleep deprivation in development of obesity, effects on appetite regulation, energy metabolism, and dietary choices

Sleep deprivation, which is a decrease in duration and quality of sleep, is a common problem in today's life. Epidemiological and interventional investigations have suggested a link between sleep deprivation and overweight/obesity. Sleep deprivation affects homeostatic and non-homoeostatic regulation of appetite, with the food reward system playing a dominant role. Factors such as sex and weight status affect this regulation; men and individuals with excess weight seem to be more sensitive to reward-driven and hedonistic regulation of food intake. Sleep deprivation may also affect weight through affecting physical activity and energy expenditure. In addition, sleep deprivation influences food selection and eating behaviours, which are mainly managed by the food reward system. Sleep-deprived individuals mostly crave for palatable energy-dense foods and have low desire for fruit and vegetables. Consumption of meals may not change but energy intake from snacks increases. The individuals have more desire for snacks with high sugar and saturated fat content. The relationship between sleep and the diet is mutual, implying that diet and eating behaviours also affect sleep duration and quality. Consuming healthy diets containing fruit and vegetables and food sources of protein and unsaturated fats and low quantities of saturated fat and sugar may be used as a diet strategy to improve sleep. Since the effects of sleep deficiency differ between animals and humans, only evidence from human subject studies has been included, controversies are discussed and the need for future investigations is highlighted.

Sleep restriction by sleep timing late night or early wake: The impact on physical activity and dietary intake in adults

PURPOSE

To date, few studies have assessed whether the timing of sleep restriction impacts physical activity and energy intake patterns. Thus, we aimed to quantify physical activity and energy intake during an early wake (EW) and late sleep (LS) period.

METHODS

Fourteen participants who met the inclusion criteria (sleep 7-9 h/night and a BMI of <40 kg/m2) participated in 3 crossover free-living conditions: normal sleep (NS, 7-9 h), EW (2-h early wake-time), and LS (2-h late to sleep) for 4 nights. Sleep duration (via Actiwatch), energy intake (via food diaries), and physical activity (via hip accelerometry) were recorded for 4 days/4 nights throughout each condition.

RESULTS

Sleep duration was reduced in both sleep restriction conditions compared to NS (p < 0.001) with no difference between sleep restriction conditions. Daily energy intake tended to increase in the LS condition (p = 0.056) but was unchanged during EW (p = 0.56). Fat (p = 0.031) and sodium (p = 0.039) intake were increased in the LS condition only compared to NS. During the EW condition, fat (p = 0.24) and sodium (p = 0.18) intake were not altered. No changes in carbohydrate or protein intake occurred between conditions. Daily steps tended to increase in the EW condition compared to NS (p = 0.058), while steps during the LS condition were unchanged (p = 0.28), with no differences between sleep restriction conditions.

CONCLUSION

The timing of sleep curtailment differentially influences physical activity and EI the following day, such that EW results in increased physical activity, while LS leads to poorer dietary choices.

Effects of sleep restriction on food intake and appetite under free-living conditions: A randomized crossover trial

To investigate changes in subjective psychological factors and dietary intake during sleep restriction, we carried out a randomized crossover trial with a 3-day sleep restriction condition (SR; 5 h of sleep) and control sleep condition (CS; 8 h of sleep). Days 3 and 4 involved free-living and laboratory (in the morning) conditions, respectively. Subjective psychological factors (hunger, appetite, desire for sweets and fatty foods, sleepiness, and fatigue) were assessed using a 0.0-10.0 cm visual analog scale (VAS) every hour throughout the day on day 3, and at 8:00 a.m. on day 4. Dietary intake on day 3 was assessed on the basis of the food purchased and eaten. Fasting blood samples were collected at 8:00 a.m. on day 4. Dietary intake during the ad libitum breakfast was assessed on day 4. The participants were 13 women and 11 men (mean age, 21.4 ± 1.0 years; mean body mass index, 19.8 ± 1.7 kg/m2). The areas under the curve 0-16 h after waking for hunger, desire for fatty foods, sleepiness, and fatigue were higher in the SR than CS on day 3 (P < 0.05). Energy and carbohydrate intakes from snacks (daytime and nighttime) on day 3 were higher in the SR than CS (P < 0.05) but total dietary intake on day 3 was not different between the conditions (P > 0.05). The 2-arachidonoylglycerol level was different between the conditions (P < 0.05), but was not associated with sweet taste preference, dietary intake, or the active ghrelin level on day 4 (P > 0.05). In conclusion, ratings for subjective psychological factors and energy and carbohydrate intakes from snacks increased in association with sleep restriction under free-living conditions.

Late, but Not Early, Night Sleep Loss Compromises Neuroendocrine Appetite Regulation and the Desire for Food

OBJECTIVE

There is evidence that reduced sleep duration increases hunger, appetite, and food intake, leading to metabolic diseases, such as type 2 diabetes and obesity. However, the impact of sleep timing, irrespective of its duration and on the regulation of hunger and appetite, is less clear. We aimed to evaluate the impact of sleep loss during the late vs. early part of the night on the regulation of hunger, appetite, and desire for food.

METHODS

Fifteen normal-weight ([mean ± SEM] body-mass index: 23.3 ± 0.4 kg/m²) healthy men were studied in a randomized, balanced, crossover design, including two conditions of sleep loss, i.e., 4 h sleep during the first night-half ('late-night sleep loss'), 4 h sleep during the second night-half ('early-night sleep loss'), and a control condition with 8h sleep ('regular sleep'), respectively. Feelings of hunger and appetite were assessed through visual analogue scales, and plasma ghrelin and leptin were measured from blood samples taken before, during, and after night-time sleep.

RESULTS

Ghrelin and feelings of hunger and appetite, as well as the desire for food, were increased after 'late-night sleep loss', but not 'early-night sleep loss', whereas leptin remained unaffected by the timing of sleep loss.

CONCLUSIONS

Our data indicate that timing of sleep restriction modulates the effects of acute sleep loss on ghrelin and appetite regulation in healthy men. 'Late-night sleep loss' might be a risk factor for metabolic diseases, such as obesity and type 2 diabetes. Thereby, our findings highlight the metabolic relevance of chronobiological sleep timing.

Connecting insufficient sleep and insomnia with metabolic dysfunction

The global epidemic of obesity and type 2 diabetes parallels the rampant state of sleep deprivation in our society. Epidemiological studies consistently show an association between insufficient sleep and metabolic dysfunction. Mechanistically, sleep and circadian rhythm exert considerable influences on hormones involved in appetite regulation and energy metabolism. As such, data from experimental sleep deprivation in humans demonstrate that insufficient sleep induces a positive energy balance with resultant weight gain, due to increased energy intake that far exceeds the additional energy expenditure of nocturnal wakefulness, and adversely impacts glucose metabolism. Conversely, animal models have found that sleep loss-induced energy expenditure exceeds caloric intake resulting in net weight loss. However, animal models have significant limitations, which may diminish the clinical relevance of their metabolic findings. Clinically, insomnia disorder and insomnia symptoms are associated with adverse glucose outcomes, though it remains challenging to isolate the effects of insomnia on metabolic outcomes independent of comorbidities and insufficient sleep durations. Furthermore, both pharmacological and behavioral interventions for insomnia may have direct metabolic effects. The goal of this review is to establish an updated framework for the causal links between insufficient sleep and insomnia and risks for type 2 diabetes and obesity.

The Role of Sleep and Eating Patterns in Adiposity Gain among Preschool-Aged Children

BACKGROUND

Short sleep duration is related to risk for obesity in preschool children. However, the underlying mechanism(s) are not clear.

OBJECTIVE

We evaluated the relationship between sleep characteristics with body composition, energetics and weight-regulating behaviors in preschool-aged children; and the longitudinal associations between children's sleep and eating patterns with body composition at 1-year follow-up.

METHODS

Data were drawn from a longitudinal study of 118 children aged 3-5 years. Sleep (duration, midpoint, regularity) and physical activity (PA) were measured by accelerometry over 6 consecutive days; total energy expenditure (TEE) using the doubly-labeled water method; body composition (fat mass, fat-free mass, and %body fat) by dual energy x-ray absorptiometry; and dietary intake (energy intake, timing) using two 24-h recalls. Multivariable regression was used to estimate interindividual associations of sleep parameters with body composition, PA, TEE and dietary outcomes; and to examine the relationship between sleep and dietary behaviors with body composition one year later.

RESULTS

Cross-sectionally, later sleep midpoint was associated with greater fat mass (0.33; 95% CI: 0.05, 0.60) and %body fat (0.92; 95% CI: 0.15, 1.70). Later sleep midpoint was associated with delayed morning (0.51; 95% CI: 0.28, 0.74) and evening meal times (0.41; 95% CI: 0.29, 0.53), higher nighttime (45.6; 95% CI: 19.7, 71.4), and lower morning (-44.8; 95% CI: -72.0, -17.6) energy intake. Longitudinally, shorter sleep duration (-0.02; 95% CI: -0.03, -0.00) and later meal timing (0.83; 95% CI: 0.24, 1.42) were associated with higher %body fat 1 year later.

CONCLUSIONS

Shorter sleep duration and later meal timing are associated with adiposity gain in preschoolers.

Interindividual differences in energy intake after sleep restriction: The role of personality and implicit attitudes toward food

Sleep restriction (SR) often leads to an increase in energy intake (EI). However, large variability in EI after SR is often observed, which suggests that individual characteristics may affect food intake. The objective of this study was to explore the influence of characteristics generally associated with risk-taking (sensitivity to reward and personality traits: impulsiveness, sensation seeking) and implicit attitudes toward food on EI after sleep loss. 17 subjects completed the NEO-PI-3, an Implicit Association Test measuring implicit attitudes towards healthy and unhealthy foods, and the Sensitivity to Punishment and Sensitivity to Reward Questionnaire. 24h Ad libitum EI was assessed following a habitual sleep night, a 50% SR with an advanced wake time, and a 50% SR with a delayed bedtime. Changes in EI between each SR condition and the control condition (ΔEI) were calculated for each subject. Despite no changes in overall EI between sleep conditions, results showed large interindividual variations (-669 to +899 kcal) across SR conditions. Regression modeling showed that a lower sensation seeking and higher favorable implicit attitudes towards unhealthy food were significantly associated with increased ΔEI in the advanced wake time condition. For the delayed bedtime, lower sensation seeking was associated with increased ΔEI while controlling for age, sex, REM sleep, and implicit attitudes. These results suggest that certain personality traits and implicit attitudes toward food are associated with changes in EI after sleep loss.

Effect of sleep duration on dietary intake, desire to eat, measures of food intake and metabolic hormones: A systematic review of clinical trials

BACKGROUND AND AIMS

Sleep, as well as diet and physical activity, plays a significant role in growth, maturation, health, and regulation of energy homeostasis. Recently, there is increasing evidence indicating a possible causal association between sleep duration and energy balance. We aimed to examine the relationship between sleep duration and food consumption, energy intake, anthropometric characteristics, and appetite-regulating hormones by randomized controlled trials (RCTs).

METHODS

Electronic literature searches were conducted on Medline, Web of Science, and Google Scholar until July 2020. The search was conducted with the following words: "Sleep Duration", "Circadian Rhythm", "Sleep Disorders" in combination with "Obesity", "Overweight", "Abdominal Obesity", "Physical Activity", "Energy Intake", "Body Mass Index", "Lipid Metabolism", "Caloric Restriction", Leptin, "Weight Gain", and "Appetite Regulation" using human studies.methods RESULTS: After screening 708 abstracts, 50 RCTs (7 on children or adolescents and 43 on adults) were identified and met the inclusion criteria. In general, the findings suggested that sleep restriction may leads to a significant increment in energy intake, fat intake, body weight, appetite, hunger, eating occasions, and portion size, while protein and carbohydrate consumption, total energy expenditure, and respiratory quotient remained unaffected as a result of sleep restriction. Serum leptin, ghrelin, and cortisol concentrations were not influenced by sleep duration as well.

CONCLUSION

Insufficient sleep can be considered as a contributing factor for energy imbalance, weight gain, and metabolic disorders and it is suggested that to tackle disordered eating it may be necessary to pay more attention to sleep duration.

THE RELATIVE REINFORCING VALUE OF SNACK FOOD IS A SIGNIFICANT PREDICTOR OF FAT LOSS IN WOMEN WITH OVERWEIGHT OR OBESITY

Reinforcing Relative Value (RRV) of food and impulsivity are associated with energy intake and obesity. The study investigated the degree to which changes in RRV and impulsivity independently or interactively predict change in body weight and composition in women with overweight or obesity engaged in either a fast or in a slow weight loss programs. Body weight, body composition, Impulsivity (Barratt Impulsiveness Scale), RRV snack (computerized Behavioural Choice Task) were measured at baseline and post-intervention in 30 women with obesity undergoing either slow (n= 14 -500 kcal/day, 20 weeks) or fast n=16 (-1000kcal/day, 10 weeks) weight reduction. No group*time effects were noted on body composition, impulsivity or RRV, so participants from both groups were pooled for analysis. Multiple regression analyses indicated that none of the impulsivity variables predicted weight- or fat mass (FM) loss. However, Δ RRV snack predicted ΔFM (r=0.40, P=0.046), whereby greater increases in RRV snack were associated with less FM loss. Results indicate that different rates of weight loss do not differentially affect RRV snack or impulsivity traits. However, changes in RRV snack predicted FM loss, suggesting that dietary interventions that either mitigate increases or foster reductions in the RRV snack may yield greater reductions in adiposity. Trial Registration clinicaltrials.gov identifier: NCT04866875 NOVELTY POINTS • No differences in RRV of food were noted between fast and slow weight loss • Weight loss from combined fast and slow groups led to a moderate-sized reduction in the total impulsivity • Greater diet-induced increases in RRV snack was associated with less body fat-loss.

Severe sleep restriction suppresses appetite independent of effects on appetite regulating hormones in healthy young men without obesity

OBJECTIVE

Several nights of moderate (4-5 hr/night) sleep restriction increases appetite and energy intake, and may alter circulating concentrations of appetite regulating hormones. Whether more severe sleep restriction has similar effects is unclear. This study aimed to determine the effects of severe, short-term sleep restriction on appetite, ad libitum energy intake during a single meal, appetite regulating hormones, and food preferences.

METHODS

Randomized, crossover study in which 18 healthy men (mean ± SD: BMI 24.4 ± 2.3 kg/m², 20 ± 2 yr) were assigned to three consecutive nights of sleep restriction (SR; 2 hr sleep opportunity/night) or adequate sleep (AS; 7-9 hr sleep opportunity/night) with controlled feeding and activity designed to maintain energy balance throughout the 3-day period. On day 4, participants consumed a standardized breakfast. Appetite, assessed by visual analogue scales, and circulating ghrelin, peptide-YY (PYY), glucagon-like peptide (GLP-1), insulin, and glucose concentrations were measured before and every 20-60 min for 4hr after the meal. Ad libitum energy and macronutrient intakes were then measured at a provided buffet lunch. Food preferences were measured by Leeds Food Preference Questionnaire (LFPQ) administered before and after the lunch.

RESULTS

Area under the curve (AUC) of postprandial hunger (-23%), desire to eat (-23%), and prospective consumption (-18%) ratings were all lower, and postprandial fullness AUC (25%) was higher after SR relative to after AS (p ≤ 0.02). Ad libitum energy intake at the lunch meal was 332 kcal [95% CI: -479, -185] (p<0.001) lower after SR relative to after AS, but relative macronutrient intakes and LFPQ scores did not differ. Postprandial glucose, insulin, PYY, GLP-1, and ghrelin AUCs did not differ between phases. However, mean concentrations of PYY (-11%) and GLP-1 (-4%) over the 4-hr testing period were lower, and glucose concentrations were 6% higher, after SR relative to after AS (p ≤ 0.01).

CONCLUSION

In contrast with reported effects of moderate sleep restriction, severe sleep restriction reduced appetite and energy intake, had no impact food preferences, and had little impact on appetite regulating hormones. Findings suggest that severe sleep restriction may suppress appetite and food intake, at least at a single meal, by a mechanism independent of changes in food preference or appetite regulating hormones.

Associations Among Sleep and Cancer Risk Behaviors: a Scoping Review of Experimental Studies in Healthy Adult Populations

BACKGROUND

Links among poor sleep and cancer risk behaviors have been largely overlooked in the context of cancer prevention and behavioral medicine. The goal of this scoping review was to determine the extent and nature of experimental studies conducted with healthy adult populations that tested the associations among poor sleep and cancer risk behaviors.

METHOD

Electronic databases and major sleep journals were searched to identify experimental studies in healthy adult samples published through January 2018. Studies examined associations among eight pairings of manipulated behaviors and outcomes ("independent variable (IV)-outcome pairs"): the impact of sleep manipulations on physical activity (PA), diet, alcohol consumption, and tobacco use outcomes; and the impact of PA, diet, alcohol consumption, and tobacco use manipulations on sleep outcomes. Studies were characterized in terms of sample characteristics; study design; IV type, dose, and duration; and outcome measurement and duration.

RESULTS

Abstracts of 5697 papers and 345 full texts were screened. Eighty-eight studies describing 125 comparisons met inclusion criteria. Only two studies tested the association between tobacco use and sleep; none tested whether sleep influenced alcohol consumption. Sample sizes were typically small, most studies used crossover designs, and studies tended to include younger and more male participants. Within each IV-outcome pair, there was substantial heterogeneity in how behaviors were manipulated, outcome measurement, and type of control group. Few studies assessed mechanisms.

CONCLUSION

There is a need for larger experimental studies with more representative samples. Overall, heterogeneity and limitations in study designs make it difficult to synthesize evidence across studies.

One-month of a low-energy diet, with no additional effect of high-protein, reduces Obstructive Sleep Apnea severity and improve metabolic parameters in obese males

PURPOSE

Obstructive Sleep Apnea (OSA) is closely associated with obesity. Weight loss ameliorates OSA and its associated metabolic disorders. A high protein intake may improve weight loss through increased energy expenditure, and fat-free mass maintenance during weight loss.

OBJECTIVES

To evaluate the effects of a low-energy, high-protein diet on OSA severity and metabolic parameters in obese men.

METHODS

Forty-five OSA obese (BMI ≥ 30 kg/m²) males were included in this randomized study and submitted to nocturnal polysomnography, body composition measured by plethysmography, biochemical analyses of blood glucose, insulin and lipids, and food intake evaluations before and after one month of a low-energy diet. Diets were designed to create a 30% deficit in total energy expenditure with 1.6 g of protein/kg/day (High Protein group - HP) or 0.8 g of protein/kg/day (Low Protein group - LP).

RESULTS

Only a time effect of the intervention was observed in body mass (-3.7 ± 2.0% for the LP group and -4.0 ± 1.5% for the HP group; p < 0.001), Body Mass Index (p < 0.001), fat mass in kg (p < 0.01) and fat-free mass in kg (p < 0.01). Significant improvements in Apnea Hypopnea Index were observed in both groups (54.0 ± 25.0 to 33.7 ± 31.7 in LP group; 39.7 ± 24.3 to 21.4 ± 25.9 in HP group; p = 0.06). Improvements of 38% and 46% in the Apnea-Hypopnea Index were observed in the LP and HP groups, respectively. Both interventions provided equivalent metabolic benefits as reductions in glucose (p < 0.001), insulin (p < 0.001), HOMA-IR (p = 0.005), triglycerides (p = 0.002), and in total cholesterol (p = 0.004).

CONCLUSION

One month of a low-energy diet resulted in significant improvements in OSA severity in obese men. Increased protein intake during a short period of low-energy diet had no further beneficial effects on OSA severity or biochemical parameters than a standard protein diet. Registered under ClinicalTrials.gov Identifier no. NCT01985035.

[Behavioral factors of sleep-related complaints and subjective poor well-being in general population]

OBJECTIVE

To validate the Scale of Behavioral Factors of Sleep Disturbances is people without diagnosed sleep disorders, as well as to reveal direct and indirect effects of sleep behavior on subjective sleep quality and well-being.

MATERIAL AND METHODS

Sample 1 included 66 people, aged 19-55 years, without diagnosed sleep disturbances who completed the Scale of Behavioral Factors of Sleep Disturbances (subscales for Taking Medications and Non-Medications, Alcohol, Tonic Drinks and Using Gadgets in the evening, Delaying Bedtime, Self-Limitations, Sleep Ritual, Adherence to the Regimen, Postponement of the Morning Rise), Insomnia Severity Index, Hospital Scale of Anxiety and Depression. Sample 2 included 174 people, aged 17-57 years, without diagnosed sleep disorders, who completed Beck's Anxiety and Depression Inventories in addition to the scales administered to sample 1. Forty-four people completed the Scale of Behavioral Factors again after two weeks.

RESULTS

The moderate reliability-consistency (α=0.62-0.93) and retest reliability of the subscales (r=0.33-0.79, p<0.01) as well as the relationship between poor sleep, especially in the evening, self-limitating behavior and sleep-related complaints of sleep, anxiety and, to a lesser extent, complaints of depressive symptoms (r=0.15-0.58, p<0.05) were revealed. All behavioral strategies, except for the sleep ritual, are characterized by an indirect effect on anxiety, depressiveness, poor well-being (|β|=0.03-0.24): the more often a person uses them, the more likely he/she has sleep-related complaints, which, in turn, is a risk factor for poorer well-being. Self-limiting behavior and delaying the morning rise are associated with a lower level of well-being, even in the absence of sleep-related complaints (β=0.23-0.34, p<0.01).

CONCLUSIONS

The Scale of Behavioral Factors of Sleep Disturbances can be used for research purposes. The results of the study suggest that the dysfunctional role of behavior on well-being is predominantly indirect (through the perpetuation of complaints), but it can also be direct (regardless of complaints of sleep disorders).

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 timing, sleep consistency, and health in adults: a systematic review

The objective of this systematic review was to examine the associations between sleep timing (e.g., bedtime/wake-up time, midpoint of sleep), sleep consistency/regularity (e.g., intra-individual variability in sleep duration, social jetlag, catch-up sleep), and health outcomes in adults aged 18 years and older. Four electronic databases were searched in December 2018 for articles published in the previous 10 years. Fourteen health outcomes were examined. A total of 41 articles, including 92 340 unique participants from 14 countries, met inclusion criteria. Sleep was assessed objectively in 37% of studies and subjectively in 63% of studies. Findings suggest that later sleep timing and greater sleep variability were generally associated with adverse health outcomes. However, because most studies reported linear associations, it was not possible to identify thresholds for “late sleep timing” or “large sleep variability”. In addition, social jetlag was associated with adverse health outcomes, while weekend catch-up sleep was associated with better health outcomes. The quality of evidence ranged from “very low” to “moderate” across study designs and health outcomes using GRADE. In conclusion, the available evidence supports that earlier sleep timing and regularity in sleep patterns with consistent bedtimes and wake-up times are favourably associated with health. (PROSPERO registration no.: CRD42019119534.)

Novelty This is the first systematic review to examine the influence of sleep timing and sleep consistency on health outcomes. Later sleep timing and greater variability in sleep are both associated with adverse health outcomes in adults. Regularity in sleep patterns with consistent bedtimes and wake-up times should be encouraged.

Hot, Tired and Hungry: The Snacking Behaviour and Food Cravings of Firefighters During Multi-Day Simulated Wildfire Suppression

Firefighters are exposed to numerous stressors during wildfire suppression, including working in hot temperatures and sleep restricted conditions. Research has shown that when sleep restricted, individuals choose foods higher in carbohydrates, fat, and sugar, and have increased cravings for calorie dense foods. However, there is currently no research on the combined effect of heat and sleep restriction on snacking behaviour. Conducting secondary analyses from a larger study, the current study aimed to investigate the impact of heat and sleep restriction on snacking behaviour and food cravings. Sixty-six firefighters completed three days of simulated physically demanding firefighting work and were randomly allocated to either the control (n = 18, CON; 19 °C, 8 h sleep opportunity), sleep restricted (n = 16, SR; 19 °C, 4-h sleep opportunity), hot (n = 18, HOT; 33 °C, 8 h sleep opportunity), or hot and sleep restricted (n = 14 HOT + SR; 33 °C, 4-h sleep opportunity) condition. During rest periods firefighters were able to self-select sweet, savoury, or healthy snacks from a ration pack and were asked to rate their hunger, fullness, and cravings every two hours (eating block). Mixed model analyses revealed no difference in total energy intake between conditions, however there was a significant interaction between eating block and condition, with those in the CON, HOT, and HOT + SR condition consuming significantly more energy between 1230 and 1430 compared to the SR condition (p = 0.002). Sleep restriction and heat did not impact feelings of hunger and fullness across the day, and did not lead to greater cravings for snacks, with no differences between conditions. These findings suggest that under various simulated firefighting conditions, it is not the amount of food that differs but the timing of food intake, with those that are required to work in hot conditions while sleep restricted more likely to consume food between 1230 and 1430. This has potential implications for the time of day in which a greater amount of food should be available for firefighters.

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.

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.

Sleep and obesity: the mediating role of health behaviors among African Americans

OBJECTIVES

To examine the role of health behaviors (eg, physical activity, sedentary behaviors, and diet) in the relationship between sleep (ie, duration and quality) and BMI among African American adults.

DESIGN

A cross-sectional self-report questionnaire included questions related to health and health-related behaviors.

SETTING

This study was based on data from the CHURCH study, which aimed to address cancer health disparities among church-going African Americans in Houston, TX.

PARTICIPANTS

African American adults were recruited from three large community churches. The sample included a total of 1837 participants (75.2% female; mean age 48.2 ± 13.7y; mean BMI 32.0 ± 7.5 kg/m²).

MEASUREMENTS

Linear regression models and path analyses controlling for demographic characteristics and depression estimated the associations between sleep and BMI as well as the mediating roles of health behaviors.

RESULTS

The average self-reported sleep duration was 6.2 ± 1.5 h/night with 61%, 35.8%, and 1.6% reporting short (≤6 h/night), normal (7-9 h/night), and long sleep (≥10 h/night), respectively. Short sleep was related to greater BMI (b = 1.37, SE = 0.38, P = .01), and the relationship was mediated by sedentary behaviors (est. = 0.08, SE = 0.04, 95% CI: 0.02, 0.17).

CONCLUSIONS

Short sleep and poor quality sleep was related to poor diet and physical activity-related health behaviors, and BMI. The link between sleep and obesity is, in part, due to energy imbalance from increased sedentary behavior.

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.

Increased energy intake following sleep restriction in men and women: A one-size-fits-all conclusion?

OBJECTIVE

This study assessed the degree of interindividual responses in energy intake (EI) to an imposed sleep restriction versus habitual sleep duration protocol. It also investigated participant (age, sex, ethnicity, and BMI) and study (study site and protocol order) characteristics as potential contributors to the variance in EI responses to sleep restriction between individuals.

METHODS

Data from two randomized crossover trials were combined. All participants (n = 43; age: 31 ± 7 years, BMI: 23 ± 2 kg/m² ) were free of medical/sleep conditions, were nonsmokers, reported not performing shift work, and had an average sleep duration of 7 to 9 hours per night. Ad libitum, 24-hour EI was objectively assessed following sleep restriction (3.5-4 hours in bed per night) and habitual sleep (7-9 hours in bed per night) conditions.

RESULTS

Large interindividual variations in EI change (ΔEI) between restricted and habitual sleep conditions were noted (-813 to 1437 kcal/d). Only phase order was associated with ΔEI (β = -568 kcal/d, 95% confidence interval for β = -921 to -215 kcal/d; P = 0.002); participants randomized to the habitual sleep condition first had greater increases in EI when sleep was restricted (P = 0.01).

CONCLUSIONS

Large interindividual variations in ΔEI following sleep restriction were noted, suggesting that not all participants were negatively impacted by the effects of sleep restriction.

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.