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Objectively measured sleep efficiency has recently been shown to be associated with health problems. Although several factors have previously been reported to be associated with sleep efficiency, most of these studies were conducted on older or younger adults, and the factors associated with sleep efficiency in healthy workers remain unknown. The aim of this study was to investigate the relationship between sleep efficiency and lifestyle factors using sleep measurement data recorded by an activity meter worn by workers. In total, 693 workers (male, 43.6%; mean age, 42.7 ± 11.3 years) were recruited from five offices in 2017. Sleep was measured over the period of 1 week by actigraphy. Workers' attributes, lifestyle habits, and occupational stress were identified using a questionnaire, and the association of sleep efficiency with lifestyle, occupational stress, and attributes was explored by logistic regression analysis. A logistic regression analysis using attributes and occupational stress as adjustment variables revealed that "longer sleeping hours on weekends than on weekdays" [odds ratios (OR), 0.66; 95% confidence interval (CI), 0.47-0.94], "water ingestion at bedtime" [OR, 2.09; 95% CI, 1.28-3.41], and "smartphone use at bedtime" [OR, 1.90; 95% CI, 1.28-2.83] were associated with decreased sleep efficiency. This study found that lifestyle habits were associated with sleep efficiency among workers. It is necessary to verify whether intervention in these lifestyle habits would contribute to the improvement of sleep efficiency in future studies., Competing Interests: Yu Ikeda, Emi Morita, Kei Muroi, Yo Arai, Tomohiko Ikeda, Tsukasa Takahashi, Nagisa Shiraki, Shotaro Doki, Daisuke Hori, Yuichi Oi, Shin-ichiro Sasahara, Asuka Ishihara, Sumire Matsumoto, Masashi Yanagisawa, Makoto Satoh, and Ichiyo Matsuzaki are members of the SLEPT Study. The authors declare no financial relationships.

Study Objectives: Postarousal hypersynchrony (PAH) is an atypical arousal pattern in children's electroencephalography. PAH is an abrupt shift to slower frequencies in arousal-related responses, appearing as slow-wave clusters. In contrast, the prevalence of PAH in healthy young adults is still unknown. Here, we examined the prevalence and characteristics of PAH in healthy young participants., Methods: Thirty healthy young participants underwent 1 night of polysomnography (13 females, 22.8 ± 2.0 years [mean ± standard deviation]). We examined the prevalence of PAH as a function of sleep stage, sleep cycle, and time course (the first or the second half). The correlation between PAH and sleep variables was examined. The percent of total sleep time in the N3 stage (%N3) was compared for each sleep cycle and time course., Results: Twenty-eight out of 30 participants exhibited PAH (4.6 ± 4.8 times per night). PAH increased significantly during the first sleep cycle and the first half-sleep period. It was observed only in nonrapid eye movement and not in rapid eye movement sleep. The number of PAHs correlated with the number of arousals and arousal indices. The %N3 increased in the first half-sleep and the first sleep cycle., Conclusions: PAH was relatively common in healthy young participants. Since PAH occurred in a state with a high prevalence of %N3, the first sleep cycle, or the first half-sleep, we suggest that PAH may be affected by the sleep homeostasis process. Since PAH occurred only in non-rapid eye movement sleep and correlated with arousal increment, it may have the function of suppressing non-rapid eye movement sleep's cortical arousal., Citation: Suzuki Y, Kawana F, Satoh M, Abe T. The abrupt shift to slower frequencies after arousal from sleep in healthy young adults. J Clin Sleep Med . 2021;17(12):2373-2381., (© 2021 American Academy of Sleep Medicine.)

Known as metabolic flexibility, oxidized substrate is selected in response to changes in the nutritional state. Sleep imposes an extended duration of fasting, and oxidized substrates during sleep were assumed to progressively shift from carbohydrate to fat, thereby gradually decreasing the respiratory quotient (RQ). Contrary to this assumption, whole-room indirect calorimetry with improved time resolution revealed that RQ re-ascended prior to awakening, and nadir of RQ in non-obese young adults occurred earlier in women than men after bedtime. The transient decrease in RQ during sleep was blunted in metabolically inflexible men with smaller amplitude of diurnal rhythm in RQ. Similarly, the effect of 10 years difference in age on RQ became significant during sleep; the decrease in RQ during sleep was blunted in older subjects. Inter-individual difference in RQ become apparent during sleep, and it might serve as a window to gain insight into the early-stage pathogenesis of metabolic inflexibility., (© 2021. The Author(s).)

Study Objectives: Although associations between sleep quality and environmental factors and nutrient intake have been reported, interactions between these factors have not been elucidated in detail. Therefore, this cross-sectional study examined the effects of regular exercise and nutrient intake on sleep quality using the Pittsburgh Sleep Quality Index (PSQI), which is the most frequently used index for sleep evaluation., Methods: The participants included 378 individuals aged 40 years or older living in Shika Town, Ishikawa Prefecture. Of these individuals, 185 met the inclusion criteria. The participants completed a self-administered questionnaire assessing lifestyle habits and frequency and duration of exercise, the PSQI, and the brief-type self-administered diet history questionnaire (BDHQ) on nutrient intake., Results: A two-way analysis of covariance on regular exercise and PSQI scores indicated that protein intake (17.13% of energy) was significantly higher in the regular exercise and PSQI ≤10 groups than in the non-regular exercise or PSQI ≥11 groups (p = 0.002). In a multiple logistic regression analysis with PSQI scores (≤10 and ≥11), protein intake was a significant independent variable in any of the models adjusted for confounding factors such as age, sex, body mass index, current smoker, and current drinker (OR: 1.357, 95% CI: 1.081, 1.704, p = 0.009) in the regular exercise group but not in the non-regular exercise group.Conclusions We identified a positive relationship between sleep quality and protein intake in the regular exercise group. These findings suggest that regular exercise at least twice a week for 30 minutes or longer combined with high protein intake contributes to good sleep quality., Competing Interests: The authors have declared that no competing interests exist.

Background: The effects of intensity, type, and time of day of physical activity on sleep are not well understood. An appropriate increase in core body temperature, due to physical activity during daytime, aids sleep in older adults. Our previous study showed that evening exercise has more positive effects on sleep quality in older adults when compared with morning exercise. However, older adults who do not exercise form a large part of the population. This study aimed to examine the distinct effects of low-intensity exercise and housework during the evening on sleep quality in older women., Methods: This randomized crossover study included 10 healthy older women aged 65-79 years. The participants engaged in low-intensity physical activity for 30 min, either aerobic exercise (70 steps per minute), housework (at the same intensity), or remained sedentary (control) 3 h before bedtime. Sleep was recorded polysomnographically, and self-reported sleep quality was assessed the next morning using the Oguri-Shirakawa-Azumi sleep inventory, Middle-Aged and Aged version (OSA-MA) questionnaire., Results: Compared with the control trial, core body temperature was significantly elevated in participants after each activity trial (0.5 ± 0.4 and 0.4 ± 0.4 °C for housework and aerobic exercise, respectively). There was a significant difference in sleep latency (14.2 ± 19.1, 9.9 ± 15.6, and 4.2 ± 3.5 min for control, housework, and aerobic exercise, respectively; ANOVA P = 0.011) among the trials. The delta power density after aerobic exercise was significantly higher than that after the control trial. We observed an increase of 53% and 15% in delta power during the 1st hour of sleep as a result of aerobic exercise and housework, respectively. The total score on OSA-MA was significantly higher after aerobic exercise (91.0 ± 5.4, 88.1 ± 6.9, and 108.6 ± 5.9 points for control, housework, and exercise, respectively)., Conclusions: Engaging in low-intensity aerobic exercise in the evening improved polysomnographic and self-reported sleep quality. Although housework increased core body temperature to the same level as that observed after aerobic exercise, self-reported sleep quality after housework was lower than that after aerobic exercise., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Women with ovulatory menstrual cycles show an increase in body temperature in the luteal phase, compared with follicular phase, particularly during the night. Several, albeit not all, studies reported higher energy expenditure in the luteal phase compared with follicular phase. Q 10 of biological reactions lies between 2.0 and 3.0, predicting a 7-12% increase in energy expenditure when body temperature rises by 1°C. In this study, temperature dependence of energy expenditure was assessed by comparing changes in sleeping energy expenditure and thermoregulation with menstrual cycle in 9 young females. Energy expenditure was measured using a metabolic chamber, in which sleep was recorded polysomnographically, and core body temperature and skin temperature were continuously monitored. Distal-to-proximal skin temperature gradient was assessed as an index of heat dissipation. In the luteal phase, a significant increase in average core body temperature (+0.27°C) and energy expenditure (+6.9%) were observed. Heat dissipation was suppressed during the first 2 hr of sleep in the luteal phase, compared with follicular phase. Rise in basal body temperature in the luteal phase was accompanied by increased energy expenditure and suppressed heat dissipation. The 6.9% increase in metabolic rate would require a Q 10 of 12.4 to be attributable solely to temperature (+0.27°C), suggesting that energy expenditure in the luteal phase is enhanced through the mechanism, dependent and independent of luteal-phase rise in body temperature presumably reflects other effects of the sex hormones., (© 2020 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.)

The majority of patients with insomnia are treated with hypnotic agents. In the present study, we evaluated the side-effect profile of an orexin receptor antagonist and γ-aminobutyric acid A (GABA A ) receptor agonist on physical/cognitive functions upon forced awakening. This double-blind, randomized, placebo-controlled, cross-over study was conducted on 30 healthy male subjects. Fifteen minutes before bedtime, the subjects took a pill of suvorexant (20 mg), brotizolam (0.25 mg), or placebo and were forced awake 90 min thereafter. Physical- and cognitive-function tests were performed before taking the pill, after forced awakening, and the next morning. Polysomnographic recordings revealed that the efficacies of the hypnotic agents in prolonging total sleep time (∼30 min) and increasing sleep efficiency (∼6%) were comparable. When the subjects were allowed to go back to sleep after the forced awakening, the sleep latency was shorter under the influence of hypnotic agents (∼2 min) compared to the placebo trial (24 min), and the rapid eye movement latency was significantly shorter under suvorexant (98.8, 81.7, and 48.8 min for placebo, brotizolam, and suvorexant, respectively). Although brotizolam significantly impaired the overall physical/cognitive performance (sum of z score) compared with placebo upon forced awakening, there was no significant difference in the total z score of performance between suvorexant and placebo. Notably, the score for static balance with the eyes open was higher under suvorexant compared to brotizolam administration. The energy expenditure was lower under suvorexant and brotizolam compared with the placebo. The effect size of brotizolam ( d = 0.24) to reduce the energy expenditure was larger than that of suvorexant ( d < 0.01)., Competing Interests: The authors declare no competing interest.

Chlorogenic acids (CGA) are the most abundant polyphenols in coffee. Continuous consumption of CGA reduces body fat and body weight. Since energy metabolism and sleep are controlled by common regulatory factors, consumption of CGA might modulate sleep. Lack of sleep has been identified as a risk factor for obesity, hypertension and type 2 diabetes. The aim of this study was to determine the effects of ingesting CGA over 5 d on energy metabolism and sleep quality in humans. A total of nine healthy subjects (four male and five female) completed a placebo-controlled, double-blinded, cross-over intervention study. Subjects consumed a test beverage containing 0 or 600 mg of CGA for 5 d. On the fifth night, subjects stayed in a whole-room metabolic chamber to measure energy metabolism; sleep was evaluated using polysomnographic recording. It was found that CGA shortened sleep latency (9 (sem 2) v. 16 (sem 4) min, P<0·05) compared with the control, whereas no effect on sleep architecture, such as slow-wave sleep, rapid eye movement or waking after sleep onset, was observed. Indirect calorimetry revealed that consumption of CGA increased fat oxidation (510 (sem 84) kJ/8 h (122 (sem 20) kcal/8 h) v. 331 (sem 79) kJ/8 h (81 (sem 19) kcal/8 h), P<0·05) but did not affect energy expenditure during sleep. Consumption of CGA enhanced parasympathetic activity assessed from heart-rate variability during sleep (999 (sem 77) v. 919 (sem 54), P<0·05). A period of 5-d CGA consumption significantly increased fat oxidation during sleep, suggesting that beverages containing CGA may be beneficial to reduce body fat and prevent obesity. Consumption of CGA shortened sleep latency and did not adversely affect sleep quality.

Energy metabolism and substrate oxidation during sleep correlate with sleep stage, suggesting that energy metabolism affects sleep architecture or vice versa. The aim of the present study was to examine whether changes in energy metabolism during sleep, induced by a high-carbohydrate or high-fat meal for dinner, affect sleep architecture. Ten healthy males participated in this study, sleeping 3 nonconsecutive nights in a whole-room calorimeter. The first night was scheduled as an adaptation to the experimental environment. The other 2 nights were experimental calorimetry in a balanced cross-over design with intrasubject comparisons. In each session, subjects comsumed a high carbohydrate (HCD: PFC=10 : 10 : 80) or high fat (HFD: PFC=10 : 78 : 12) meal at 2000 h and slept with a polysomnographic recording in a metabolic chamber for indirect calorimetry (0000 h to 0800 h). Slow wave sleep was decreased during the first sleep cycle and not changed during the second or third sleep cycle under HCD conditions compared with those of HFD. Energy expenditure was not affected by dietary condition but substrate oxidation reflected differences in dietary composition of the dinner during the first and second sleep cycle. The present study suggested the possibility that substrate availability during sleep affects substrate oxidation during sleep, and affects sleep architecture during the first sleep cycle.

The purpose of this study was to examine metabolic rate and substrate oxidation during sleep in relation to time of sleep and sleep stage. Twelve male subjects free from sleep-disordered breathing slept for 469 +/- 8.7 (mean +/- SE) minutes until natural awakening in a whole-body indirect calorimeter, and polysomnographic documentation of sleep was recorded. Energy expenditure decreased during the first half of the night, reached a nadir (a 35% decrease), and remained relatively stable until awakening. Similarly, fat oxidation decreased from the onset of sleep. On the other hand, carbohydrate oxidation showed no remarkable changes from the onset of sleep but began to increase before awakening. Because distribution of sleep stages is not uniform throughout the night, with rapid-eye-movement (REM) sleep tending to appear later in the sleep, effect of sleep stage on energy metabolism was isolated by analysis of covariance with time as a covariate. Subsequent comparison of metabolic rate by 1-way analysis of variance with Bonferroni post hoc analysis revealed that energy expenditure during REM sleep was significantly greater than that during sleep stages 2 and 3/4 (stage 2, 25.248 +/- 0.961; stage 3/4, 24.825 +/- 0.935; REM, 25.712 +/- 0.928 kcal kg(-1) fat-free mass d(-1)). Carbohydrate oxidation during REM sleep was significantly greater than that during sleep stage 3/4 (stage 3/4, 12.229 +/- 1.071; REM, 13.986 +/- 1.291 kcal kg(-1) fat-free mass d(-1)). Respiration quotient was statistically different among sleep stages, but Bonferroni post hoc analysis failed to identify significant differences (stage 2, 0.850 +/- 0.010; stage 3/4, 0.846 +/- 0.011; REM, 0.861 +/- 0.013). The increases in energy expenditure and carbohydrate oxidation during REM sleep are consistent with a notion that changes in energy metabolism in brain are manifested as small fluctuations in whole-body energy metabolism during sleep.

This study aimed to determine the prevalence and risk factors of poor subjective sleep quality in elite judo athletes. A subjective cross-sectional questionnaire survey was conducted with 106 elite judo athletes who participated in the training camp of the Japanese national team. Eighty-six respondents (men: 52.3%; average age: 22.9 ± 3.1 years) with complete responses were included in the analysis (valid response rate: 81.1%). Subjective sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI). The prevalence of poor sleep quality (PSQI score ≥ 5.5), the mean PSQI score, and subscale scores were investigated. Relationships between poor sleep quality and attributes, lifestyle habits, competition-based activities, and psychological distress were explored using Fisher's exact tests and multivariate logistic regression analysis. Thirty-five respondents (40.7%) reported poor sleep quality. The percentage and subscale scores of the respondents for sleep latency, sleep duration, and daytime dysfunction were higher than those of the population of Japanese national-level athletes. The mean PSQI score of the respondents was similar to that of some elite athlete populations but higher than those of others. Multivariate logistic regression analysis revealed that psychological distress was associated with poor sleep quality. In conclusion, the prevalence of poor subjective sleep quality in elite judo athletes was suggested to be similar or higher among elite athlete population. Sleep latency, sleep duration, and daytime dysfunction status were worse in elite judo athletes than in Japanese national-level athletes. Psychological distress was a risk factor for poor subjective sleep quality in elite judo athletes. [ABSTRACT FROM AUTHOR]

Research on mental health in working populations has predominantly focussed on negative outcomes, while studies on the positive aspects of life remain very limited, especially in Japan. Although morningness has recently been considered a factor for being happy, the role of sleep characteristics as it relates to the association between morningness and happiness has not been substantiated. The aim of this study is to investigate the associations between diurnal preference and level of subjective happiness in healthy, full-time, daytime workers in Japan. We also tested the moderation effect of sleep parameters on the relationship between diurnal preference and subjective happiness. This is an exploratory analysis from the cross-sectional data of the SLeep Epidemiology Project at the University of Tsukuba (SLEPT Study). Subjective happiness was evaluated using a single-item question. Diurnal preference was assessed using the Morningness-Eveningness Questionnaire (MEQ), in which higher scores indicate greater tendency to have morning preference. The participants underwent assessment of sleep parameters for 7 consecutive days using a waist-worn actigraphy device and kept a sleep diary. Sleep parameters investigated were subjective sleep quality, sleep disturbance, daytime sleepiness, weekend oversleep, total sleep time, sleep onset time, wake time, and sleep efficiency. A total of 205 males (average 42.6 ± 10.4 years) and 272 females (41.1 ± 9.8 years) were eligible for analysis. Hierarchical liner regression analysis was used to show the relationships of subjective happiness with MEQ score, and the sleep parameters. Further, moderation analysis was conducted by adding the interaction between MEQ score and the sleep parameters. After adjusting for age, psychological distress, self-rated health, and occupational stress, we found that subjective happiness was significantly associated with higher MEQ score and sleep efficiency but only in female. The moderating role of sleep parameters was not found. We discussed the implications of the obtained results and a possible strategy to maintain and improve subjective happiness of female workers who have evening preference. [ABSTRACT FROM AUTHOR]

Exercise can improve sleep by reducing sleep latency and increasing slow-wave sleep (SWS). Some studies, however, report adverse effects of exercise on sleep architecture, possibly due to a wide variety of experimental conditions used. We examined the effect of exercise on quality of sleep using standardized exercise parameters and novel analytical methods. In a cross-over intervention study we examined the effect of 60 min of vigorous exercise at 60% V ˙ O 2 max on the metabolic state, assessed by core body temperature and indirect calorimetry, and on sleep quality during subsequent sleep, assessed by self-reported quality of sleep and polysomnography. In a novel approach, envelope analysis was performed to assess SWS stability. Exercise increased energy expenditure throughout the following sleep phase. The subjective assessment of sleep quality was not improved by exercise. Polysomnography revealed a shorter rapid eye movement latency and reduced time spent in SWS. Detailed analysis of the sleep electro-encephalogram showed significantly increased delta power in SWS (N3) together with increased SWS stability in early sleep phases, based on delta wave envelope analysis. Although vigorous exercise does not lead to a subjective improvement in sleep quality, sleep function is improved on the basis of its effect on objective EEG parameters. [ABSTRACT FROM AUTHOR]

Objectives: The control of sleep/wakefulness is associated with the regulation of energy metabolism. The present experiment was designed to assess the effect of nocturnal blue light exposure on the control of sleep/wakefulness and energy metabolism until next noon. Methods: In a balanced cross-over design, nine young male subjects sitting in a room-size metabolic chamber were exposed either to blue LEDs or to no light for 2 h in the evening. Wavelength of monochromatic LEDs was 465 nm and its intensity was 12.1 μW/cm. Results: During sleep, sleep architecture and alpha and delta power of EEG were similar in the two experimental conditions. However, the following morning, when subjects were instructed to stay awake in a sitting position, duration judged as sleep at stages 1 and 2 was longer for subjects who received than for those who received no light exposure. Energy metabolism during sleep was not affected by evening blue light exposure, but the next morning energy expenditure, oxygen consumption, carbon dioxide production and the thermic effect of breakfast were significantly lower in subjects who received blue light exposure than in those who received no light exposure. Conclusions: Exposure to low intensity blue light in the evening, which does not affect sleep architecture and energy metabolism during sleep, elicits drowsiness and suppression of energy metabolism the following morning. [ABSTRACT FROM AUTHOR]