Polyphasic Research Articles

Sleep pattern in the dromedary camel: a behavioral and polysomnography study.

To investigate sleep patterns in the camel by combining behavioral and polysomnography (PSG) methods. A noninvasive PSG study was conducted over four nights on four animals. Additionally, video recordings were used to monitor the sleep behaviors associated with different vigilance states. During the night, short periods of sporadic sleep-like behavior corresponding to a specific posture, sternal recumbency (SR) with the head lying down on the ground, were observed. The PSG results showed rapid shifts between five vigilance states, including wakefulness, drowsiness, rapid eye movement (REM) sleep, non-REM (NREM) sleep, and rumination. The camels typically slept only 1.7 hours per night, subdivided into 0.5 hours of REM sleep and 1.2 hours of NREM sleep. Camels spent most of the night being awake (2.3 hours), ruminating (2.4 hours), or drowsing (1.9 hours). Various combinations of transitions between the different vigilance states were observed, with a notable transition into REM sleep directly from drowsiness (9%) or wakefulness (4%). Behavioral postures were found to correlate with PSG vigilance states, thereby allowing a reliable prediction of the sleep stage based on SR and the head position (erected, motionless, or lying down on the ground). Notably, 100% of REM sleep occurred during the Head Lying Down-SR posture. The camel is a diurnal species with a polyphasic sleep pattern at night. The best correlation between PSG and ethogram data indicates that sleep duration can be predicted by the behavioral method, provided that drowsiness is considered a part of sleep.

Seasonal variation and sleep patterns in a hot climate Arab Region.

To describe the effect of seasonal variations on sleep patterns in a hot climate Arab region. This is a cross-sectional study that included healthy Omani subjectsof both genders between ages 18 and 59 years. Data for sleep pattern identification in summer and winter were collected from participants using an actigraphy wristband. Among 321 participants, in summer seasons, apolyphasic sleep pattern (40%) prevailed over other sleep patterns (P < 0.001). While in the winter season, monophasic sleep (31%) was the dominant pattern (P < 0.001). Subjects slept longer during the winter seasons with total hours of sleep during the day 48 min longer than in the summer, though the difference was not statistically significant (P > 0.05), while siesta duration in the summer was significantly longer (13 min, P < 0.01). In summer, the sleep quality was good (PSQI ≤ 5); however, it was poor (PSQI > 5) in winter (P < 0.05). Night sleep duration, daytime sleepiness, and sleep latency were not statistically different between the summer and winter seasons. Sleep patterns may be influenced by seasonal changes. A polyphasic sleep pattern prevailed in summer while a monophasic patternwas the predominant sleep pattern in winter. In summer, the sleep quality was good and the siesta duration was longer compared to the winter.

Association Between Subjective-Objective Discrepancy of Sleeping Time and Health-Related Quality of Life: A Community-Based Polysomnographic Study.

This study aimed to investigate the existence of a difference in quality of life (QOL) between individuals with and without significant subjective-objective discrepancy (SOD) in total sleep time (TST). From the Sleep Heart Health Study 2, 2540 individuals who had completed polysomnography, a morning sleep survey, and the 36-item Short-Form Health Survey (SF-36) were included in the analyses. The participants were classified as normoestimators (estimation of TST <±60 minutes), underestimators (underestimation of TST ≥60 minutes), or overestimators (overestimation of TST ≥60 minutes). The standardized SF-36 QOL scores were compared among the three groups. An adjusted partial correlation analysis was conducted between SOD and QOL. Of the 2540 participants, 1617 (63.7%), 433 (17.0%), and 490 (19.3%) were assigned to the normoestimator, underestimator, and overestimator groups, respectively. The bodily pain and social functioning components of the SF-36 score were significantly lower in the underestimators than in the normoestimators, whereas the physical functioning component was significantly lower in the overestimators than in the normoestimators. The absolute value of SOD in the TST showed a significant negative correlation with the physical and mental components of the SF-36. QOL was significantly better in the normoestimator than in the other groups and linearly correlated with the absolute value of SOD. This study suggests that a high prevalence of positive and negative sleep misperception in a community population can be a potential factor associated with poor QOL and potential comorbidities.

Impact of sleep timing on attention, sleepiness, and sleep quality among real-life night shift workers with shift work disorder: a cross-over clinical trial.

To examine the effect of sleep timing intervention on sleep quality, attention, and sleepiness at work among night shift workers with shift work disorder. We recruited 60 real-life night shift workers through advertisements to participate this cross-over clinical trial. Shift work disorder was confirmed with interview and sleep log. Participants were designated to follow evening sleep (15:00-23:00) and morning sleep (09:00-17:00) schedules in a randomized order. Chronotype was confirmed by the Munich Chronotype Questionnaire. Sleep behaviors and light exposure were recorded using actigraphy. Outcome measures were sleepiness evaluated by the Karolinska Sleepiness Scale, sleep quality evaluated by the Pittsburgh Sleep Quality Index, and attention performance assessed with psychomotor vigilance test. Differences in outcome between the morning and evening sleep schedules were compared using repeated measures ANOVA. The participants slept for longer durations during evening sleep schedules compared with morning sleep schedules. Lower sleepiness scores, higher sleep quality, and shorter reaction times and less lapse numbers in the psychomotor vigilance test were observed for participants during evening sleep schedules than morning sleep schedules after adjustment for light exposure and sleep duration. Significant interaction effects were observed for reaction time and lapse number between chronotype and sleep schedule, where the differences between sleep schedules were most prominent among those with late chronotypes. It is recommended that night shift workers with shift work disorder arrange to sleep in the evening instead of the morning for better sleep and attention performance, especially those with late chronotypes. Sleep Schedule Intervention Study Among Night Shift Workers, https://clinicaltrials.gov/ct2/show/NCT04160572, ClinicalTrials.gov Identifier: NTC04160572.

Effects of sleep disturbance on neuropsychological functioning in patients with pediatric brain tumor.

While the effects of sleep on cognition in typically developing children are well established, there is a paucity of research in patients with pediatric brain tumor (PBT), despite their increased risk for sleep-related disturbances. The aim of this retrospective study was to examine the impact of sleep factors on patient-reported outcome (PRO) measures, including adaptive and executive functioning within this population. 133 patients with PBT (52% male) ages 5-23 (x̄ = 12.8years;SD = 4.5years) underwent neuropsychological evaluation, including assessment of adaptive and executive functioning. Subjective sleep concerns, nocturnal sleep duration, and daytime sleep behavior were also collected and compared to age-based guidelines. Nearly 30% of patients endorsed subjective sleep concerns, while the sample as a whole reported reduced nocturnal sleep duration (approximately one hour below age-based recommendations). Despite the expectation for monophasic sleep by age five, nearly half of the sample reported consistent daytime napping. Inadequate sleep predicted decreased adaptive functioning, F(1, 56) = 4.23, p = .022 (R2 = .07), as well as increased symptoms of executive dysfunction, F(1, 108) = 3.51, p = .003 (R2 = .03). Patients with PBT demonstrate several aspects of abnormal sleep, which are associated with poorer long-term PROs. Further exploration of diagnostic, treatment-related, and demographic variables will be needed to better understand these relationships among patients with PBT in order to inform appropriate interventions.

Determining the Optimal Sleep Pattern to Promote Glymphatic Clearance of Amyloid-Beta in Individuals at Risk for Alzheimer's Disease: A Research Protocol

Introduction: Neurodegenerative disorders such as Alzheimer’s disease (AD) are increasingly prevalent amongst older populations. Sleep irregularities are one of the chief complaints in people diagnosed with sleep disorders. Sleep has been hypothesized to ensure metabolic homeostasis and remove neurotoxic waste. Inadequate sleep leads to an accumulation of Amyloid-Beta (Aβ) levels which is associated with neurodegenerative diseases including AD and other dementias. Sleep is the driver of the glymphatic system, located in the perivascular space. The glymphatic system eliminates soluble proteins, including Aβ, from the central nervous system; transporting cerebrospinal fluid through the brain; and distributing macromolecules across the brain. This research proposal aims to identify optimal sleep patterns that decrease neurodegeneration by increasing glymphatic system functioning. Methods: This study will be an ad-hoc study conducted over a 6-month period utilizing participants who have reported a family history of AD. Aß accumulation and cortisol levels will be measured to identify signs of neurodegeneration using brain scans, such as Positron Emission Tomography, and blood tests. Other parameters such as memory, energy rating, and sleep latency will be measured. Results: Reduced slow-wave sleep may lead to a disruption in the glymphatic system. Monophasic sleep is said to have the most slow-wave sleep, and least rapid eye movement sleep which is most similar to wakefulness. Therefore, we hypothesize that monophasic sleep will slow neurodegeneration compared to biphasic and polyphasic sleep, contrary to popular belief that biphasic sleep is more beneficial than monophasic sleep. Discussion: In this experiment, we expect to see increased glymphatic clearance after monophasic sleep. There are many factors that can impact sleep patterns and glymphatic clearance including work style, environment, culture, race, sex, and genetic markers for AD. Conclusion: Further research that applies this suggested methodology should account for these variabilities when making conclusions on the optimal sleep pattern for plaque clearance in the brain. This proposal may improve research on AD by identifying the effects different sleep patterns have on the brain and neurodegeneration. Future research may study changes in sleep habits as a preventative measure for individuals who are at risk for or have been diagnosed with AD.

P083 Age of Nap Cessation and Short-term Social-Emotional Functioning in Early Childhood

Abstract Background Daytime nap cessation, in which sleep transitions from biphasic to monophasic sleep, is a common feature of early childhood sleep patterns. Yet, to date, understanding of the meaning of this transition for children’s development is not well understood. The aim of this study is to investigate the relationship between the age of nap cessation and behavioral and social functioning in young children. Methods Parent report data from the Effective Early Educational Experiences (E4Kids) study of N=1700 children from across Queensland and Victoria is analysed. Data on age of nap cessation, Strengths and Difficulties Questionnaire (SDQ), and Social Skills Improvement Scale (SSIS) is examined to determine whether age of nap cessation is associated with internalizing and externalizing behaviour and social skills in early childhood. Progress to date Data collection and cleaning are complete. Initial descriptive analyses and identification of significant covariates are underway, and final regressions will be run shortly. Intended outcome/ Impact This study provides new evidence on the relationship between age of napping cessation and social-emotional outcomes in young children. Such evidence is important for building an understanding of the role of sleep cessation in children’s early development, and to inform practitioners and parents responsible for supporting children’s sleep.

Sleep in the lesser mouse-deer (Tragulus kanchil).

The mouse-deer or chevrotains are the smallest of the ungulates and ruminants. They are characterized by a number of traits which are considered plesiomorphic for the Artiodactyla order. The objective of this study was to examine sleep in the lesser mouse-deer (Tragulus kanchil), which is the smallest in this group (body mass < 2.2 kg). Electroencephalogram, nuchal electromyogram, electrooculogram, and body acceleration were recorded in four adult mouse-deer females using a telemetry system in Bu Gia Map National Park in Vietnam. The mouse-deer spent on average 49.7 ± 3.0% of 24 h in non-rapid eye movement (NREM) sleep. REM sleep occupied 1.7 ± 0.3% of 24 h or 3.2 ± 0.5% of total sleep time. The average duration of REM sleep episodes was 2.0 ± 0.2 min, the average maximum was 5.1 ± 1.1 min, and the longest episodes lasted 8 min. NREM sleep occurred in sternal recumbency with the head held above the ground while 64.7 ± 6.4% of REM sleep occurred with the head resting on the ground. The eyes were open throughout most of the NREM sleep period. The mouse-deer displayed polyphasic sleep and crepuscular peaks in activity (04:00-06:00 and 18:00-19:00). The largest amounts of NREM occurred in the morning (06:00-09:00) and the smallest before dusk (at 04:00-06:00). REM sleep occurred throughout most of the daylight hours (08:00-16:00) and in the first half of the night (19:00-02:00). We suggest that the pattern and timing of sleep in the lesser mouse-deer is adapted to the survival of a small herbivorous animal, subject to predation, living in high environmental temperatures in the tropical forest undergrowth.

Suppressing the Morning Cortisol Rise After Memory Reactivation at 4 A.M. enhances Episodic Memory Reconsolidation in Humans.

Evidence from animal and human research shows that established memories can undergo changes after reactivation through a process called reconsolidation. Alterations of the level of the stress hormone cortisol may provide a way to manipulate reconsolidation in humans. Here, in a double-blind, within-subject design, we reactivated a 3-d-old memory at 3:55 A.M. in sixteen men and four women, immediately followed by oral administration of metyrapone versus placebo, to examine whether metyrapone-induced suppression of the morning cortisol rise may influence reconsolidation processes during and after early morning sleep. Crucially, reactivation followed by cortisol suppression versus placebo resulted in enhanced memory for the reactivated episode tested 4 d after reactivation. This enhancement after cortisol suppression was specific for the reactivated episode versus a non-reactivated episode. These findings suggest that when reactivation of memories is immediately followed by suppression of cortisol levels during early morning sleep in humans, reconsolidation processes change in a way that leads to the strengthening of episodic memory traces.SIGNIFICANCE STATEMENT How can we change formed memories? Modulation of established memories has been long debated in cognitive neuroscience and remains a crucial question to address for basic and clinical research. Stress-hormone cortisol and sleep are strong candidates for changing consolidated memories. In this double-blind, placebo-controlled, within-subject pharmacological study, we investigate the role of cortisol on the modulation of reconsolidation of episodic memories in humans. Blocking cortisol synthesis (3 g metyrapone) during early morning sleep boosts memory for a reactivated but not for a non-reactivated story. This finding contributes to our understanding of the modulatory role of cortisol and its circadian variability on reconsolidation, and moreover can critically inform clinical interventions for the case of memory dysfunctions, and trauma and stress-related disorders.

The Human Sleep Paradox: The Unexpected Sleeping Habits ofHomo sapiens

The human sleep pattern is paradoxical. Sleep is vital for optimal physical and cognitive performance, yet humans sleep the least of all primates. In addition, consolidated and continuous monophasic sleep is evidently advantageous, yet emerging comparative data sets from small-scale societies show that the phasing of the human pattern of sleep–wake activity is highly variable and characterized by significant nighttime activity. To reconcile these phenomena, the social sleep hypothesis proposes that extant traits of human sleep emerged because of social and technological niche construction. Specifically, sleep sites function as a type of social shelter by way of an extended structure of social groups that increases fitness. Short, high-quality, and flexibly timed sleep likely originated as a response to predation risks while sleeping terrestrially. This practice may have been a necessary preadaptation for migration out of Africa and for survival in ecological niches that penetrate latitudes with the greatest seasonal variation in light and temperature on the planet.

609 Comparing parental sleep goals for younger versus older toddlers

Abstract Introduction This study aimed to assess parental sleep goals, comparing younger (12-23.9-month-olds) and older toddlers (24-35.9-month-olds) in consideration of developmental differences. Methods Parents (98.0% mothers) of 401 toddlers (12–35 mos; M=22.49 mos; 49% male) in the US completed an online survey, including an abbreviated Brief Infant Sleep Questionnaire and a list of 58 desired areas of change (DACs). There were 230 one-year-olds (1yos; M=17.42mos) and 171 two-year-olds (2yos; M=29.30mos), with no difference in parent age between groups (M=34.41 years). Results 25.7% reported a perceived sleep-problem, whereas 94.8% indicated at least one sleep-related DAC. Parents of one- and two-year-olds reported similar rates of DAC for overnight sleep (58% vs. 49%), morning sleep (55% vs. 52%), and naps (70% vs. 64%), p&amp;gt;.05. Parents of 2yos, however, reported bedtime as a DAC at a higher rate (59% vs. 79%), p&amp;lt;.001. Twenty-five percent of specific bedtime DACs (n=8) were endorsed by ≥10% of parents. Parents endorsed falling asleep without an adult (17% of 1yos vs. 22% of 2yos) and falling asleep without nursing (10% vs. 9%) at similar rates, p&amp;gt;.05. Parents of two-year-olds were more likely to endorse: getting through bedtime routine quickly/easily without stalling (10% vs. 30%,), earlier bedtime (10% vs. 24%), falling asleep faster at bedtime (24% vs. 10%), falling asleep without a pacifier (11% vs. 19%), falling asleep faster while alone (8% vs. 16%), and falling asleep without stalling/making requests (3% vs. 18%), p&amp;lt;.05. Conclusion The majority of parents of toddlers endorsed a sleep-related desired area of change, with two-thirds wanting to change something about bedtime and naps, and over half wanting to change something about overnight and morning sleep. Parents of older toddlers (2yos) were more likely to desire changes at bedtime than parents of younger toddlers (1yos), especially related to stalling and discontinuing pacifier use. As toddlers age, bedtime problems are more likely. Health care providers should be aware of developmental changes, such as increased language and assertions of independence, that seem to mostly affect bedtime when addressing sleep issues in toddlers. Support (if any) Johnson &amp; Johnson Consumer Inc., Skillman, NJ, USA.

An Asymmetrical Hypothesis for the NREM-REM Sleep Alternation-What Is the NREM-REM Cycle?

Since the discovery of rapid eye movement (REM) sleep (Aserinsky and Kleitman, 1953), sleep has been described as a succession of cycles of non-REM (NREM) and REM sleep episodes. The hypothesis of short-term REM sleep homeostasis, which is currently the basis of most credible theories on sleep regulation, is built upon a positive correlation between the duration of a REM sleep episode and the duration of the interval until the next REM sleep episode (inter-REM interval): the duration of REM sleep would therefore predict the duration of this interval. However, the high variability of inter-REM intervals, especially in polyphasic sleep, argues against a simple oscillator model. A new “asymmetrical” hypothesis is presented here, where REM sleep episodes only determine the duration of a proportional post-REM refractory period (PRRP), during which REM sleep is forbidden and the only remaining options are isolated NREM episodes or waking. After the PRRP, all three options are available again (NREM, REM, and Wake). I will explain why I think this hypothesis also calls into question the notion of NREM-REM sleep cycles.

Adverse impact of polyphasic sleep patterns in humans: Report of the National Sleep Foundation sleep timing and variability consensus panel

Polyphasic sleep is the practice of distributing multiple short sleep episodes across the 24-hour day rather than having one major and possibly a minor (“nap”) sleep episode each day. While the prevalence of polyphasic sleep is unknown, anecdotal reports suggest attempts to follow this practice are common, particularly among young adults. Polyphasic-sleep advocates claim to thrive on as little as 2 hours of total sleep per day. However, significant concerns have been raised that polyphasic sleep schedules can result in health and safety consequences. We reviewed the literature to identify the impact of polyphasic sleep schedules (excluding nap or siesta schedules) on health, safety, and performance outcomes. Of 40,672 potentially relevant publications, with 2,023 selected for full-text review, 22 relevant papers were retained. We found no evidence supporting benefits from following polyphasic sleep schedules. Based on the current evidence, the consensus opinion is that polyphasic sleep schedules, and the sleep deficiency inherent in those schedules, are associated with a variety of adverse physical health, mental health, and performance outcomes. Striving to adopt a schedule that significantly reduces the amount of sleep per 24 hours and/or fragments sleep into multiple episodes throughout the 24-hour day is not recommended.

Assessment of morning sleep propensity with lemborexant in adults with insomnia disorder in a randomized, placebo-controlled crossover study.

To evaluate effects of lemborexant (LEM), a dual orexin receptor antagonist, on next-morning sleep propensity assessed by a modified Multiple Sleep Latency Test (M-MSLT) in adults with insomnia disorder. Study 107 (E2006-A001-107) was a phase 1, randomized, double-blind, four-period crossover study. Subjects (n = 69) received oral single-dose placebo, LEM 5 mg (LEM5), and LEM 10 mg (LEM10) at bedtime in periods 1-3 in a randomized crossover and open-label flurazepam 30 mg in period 4. After an 8-hour overnight sleep opportunity, the M-MSLT measured average sleep onset latency (SOL). Mean change from baseline in average SOL versus placebo of -6.0 min or more was considered clinically meaningful. Other sleep propensity assessments included the proportion of subjects with average SOL >6 min shorter than placebo. LEM plasma concentrations, safety, and tolerability were also assessed. M-MSLT assay sensitivity was confirmed by a clinically meaningful decrease in average SOL with flurazepam versus placebo (least squares mean [LSM] difference -6.06 min; 1-sided p < 0.0001). In contrast, decreases in average SOL with LEM5 (LSM difference vs. placebo -1.15 min; 1-sided p = 0.0262) and LEM10 (-3.48 min; p < 0.0001) did not meet the predefined threshold for a clinically meaningful effect (LEM5, -2.12; LEM10, -4.46). Some individuals did experience higher sleep propensity (average SOL >6.0 min shorter than placebo), particularly with LEM10 (LEM10, 29.4%; LEM5, 13.2%). In contrast to flurazepam, LEM5 and LEM10 did not show clinically meaningful mean increases in next-morning sleep propensity versus placebo. The possibility that some subjects may experience residual morning effects cannot be excluded. Clinical trial registration: ClinicalTrials.gov, NCT02350309.

Comparison of Royal Canadian Navy Watchstanding Schedules.

Life on board a naval vessel is exceptionally demanding. Workdays for naval sailors can quite easily become 18+ hours long when watch schedules, training, and drills/evolutions are taken into account. Rotating watches and short off-watch periods can force sailors into a biphasic sleep pattern that is not sufficiently restful or a rotating pattern that is impossible to adapt to. Six different watch systems were evaluated over four separate at-sea trials. Engineering and tactical/combat departments have had different watch systems in the past because of constraints related to the specific environment in which they work. Therefore, two of the watch systems were engineering-specific watch evaluations, three of the systems were specific to tactical/combat departments, and one watch system was evaluated with the entire company of the naval vessel. Both two-section (1-in-2) watch systems and three-section (1-in-3) watch systems were evaluated, which involve two or three shifts of sailors rotating through a full continuous 24-h day, respectively. Moving beyond three rotations of sailors is impossible on Canadian naval vessels due to bunk space and other limitations. The best watch system that we evaluated with respect to fatigue and quality of life at sea was the 1-in-3 straight 8-h shift system that was tested for the entire ships' company. The system has a single 8-h daily watch obligation (red watch, 4:00 am-12:00 pm; white watch 12:00 pm-8:00 pm; and blue watch, 8:00 pm-4:00 am). The best 1-in-2 system was the 8-4-4-8 system in which sailors are on-watch for 8 h, off-watch for 4 h, on-watch for 4 h, and then rest for 8 h. Both of these two systems have the advantage of equitably sharing the Window of Circadian Low (from about midnight to about 8:00 am), especially when melatonin concentration in the body is usually at its peak, between 2:00 am and 6:00 am. The goal of this work was to comprehensively evaluate both submarine and surface fleet watch systems. We were able to develop alternative watch systems that increased Royal Canadian Navy operational readiness and improved the quality of life of our sailors at sea.

Agreement analysis of sleep patterns between self-reported questionnaires and actigraphy in adults.

To investigate the agreement in sleep pattern recording by self-reported sleep questionnaires and actigraphy in adults. This is a cross-sectional study. Men and women who metinclusion criteria were recruited for this study. The inclusion criteria were apparently healthy Omani nationalsages 19 to 50 years. Sleep questionnaires were randomly distributed in Muscat either directly or via electronic and paper announcements. Data were collected from the participants using the self-reported questionnaires with four piloted questions for sleep pattern identification and through the actigraphy wristband given to subjects to wear for a week. Cohen's kappa test was performed for agreement analysis. A total of 964 Omani subjects between ages 18 and 59 years of both genders were recruited and completed the questionnaires successfully. Out of these, only 321 subjects wore the actigraphy wristband for 1 week (response rate = 33%). Agreement analysis reported a mild level of agreement for the monophasic (41%), moderate level for biphasic (59%), and good level for polyphasic (70%) sleep patterns. The overall agreement level of sleep patterns between the two methods was 57%. There is a low specificity of self-reported assessment in reporting sleep pattern. The average agreement level of subjective versus objective assessments of sleep patterns was moderate at 57% and self-reported sleep pattern is not specific. The study recommends the use of actigraphy along with sleep questionnaires for accurate assessment of sleep patterns in cohort studies.

Sleep fragmentation and lucid dreaming.

Lucid dreaming-the phenomenon of experiencing waking levels of self-reflection within one's dreams-is associated with more wake-like levels of neural activation in prefrontal brain regions. In addition, alternating periods of wakefulness and sleep might increase the likelihood of experiencing a lucid dream. Here we investigate the association between sleep fragmentation and lucid dreaming, with a multi-centre study encompassing four different investigations into subjective and objective measures of sleep fragmentation, nocturnal awakenings, sleep quality and polyphasic sleep schedules. Results across these four studies provide a more nuanced picture into the purported connection between sleep fragmentation and lucid dreaming: While self-assessed numbers of awakenings, polyphasic sleep and physiologically validated wake-REM sleep transitions were associated with lucid dreaming, neither self-assessed sleep quality, nor physiologically validated numbers of awakenings were. We discuss these results, and their underlying neural mechanisms, within the general question of whether sleep fragmentation and lucid dreaming share a causal link.

Sugar-sweetened beverages as risk factor of central obesity among women in reproductive age

Background: Several risk factors for central obesity include high Sugar-sweetened Beverages (SSBs) intake, lack of physical activity, and lack of sleep duration. High fructose corn syrup, the sweetener used in SSBs, increase body weight because of the bad effect of insulin secretion and leptin release. The fructose from this beverage can increase visceral adiposity accumulation. Objectives: This study aimed to analyze the intake of Sugar-sweetened Beverages (SSBs), physical activity, and sleep duration as risk factors for central obesity among women in the reproductive AgeMethods: This study used case-control design consists of 38Subjects in case and control groups. All women were in childbearing age (20-29 years) selected using a simple random sampling technique. The data taken were weight, height, waist circumference, and hip circumference. Food intake and sugar-sweetened beverage intake were obtained by using Semi-Quantitative Food Frequency (SQ-FFQ) questionnaire. Physical activity data were obtained using the International Physical Activity Questionnaire (IPAQ) questionnaire. Sleep duration data were obtained using the Pittsburgh Sleep Quality Index (PSQI). Chi-Square test and logistic regression were used to analyze the data.Results: There were a significant relationship between Sugar Sweetened Beverages intake (p = 0.002, OR =5.926), energy intake of SSBs (p = 0.035, OR = 2.979) physical activity (p = 0.035, OR = 0.3111), duration of morning sleep / afternoon (p = 0.000; OR = 9.44) and sleep duration (p = 0.028, OR = 4.42) with central obesity. But there were no significant relationship between energy intake (p = 0.375), carbohydrates (p = 0.1), protein (p = 0.3), fat (p = 0.1) and fibers with central obesity.Conclusion: High intake of sugar-sweetened beverages, short duration of night's sleep and the duration&gt;2 hours/day of a long day sleep are risk factors for increasing the incidence of central obesity among Women in reproductive Age.

0300 The Circadian Timing of Sleep Affects the Rate of Accumulation of Neurobehavioral Impairment Across Days of Sleep Restriction

Abstract Introduction Chronic restriction of nighttime sleep to less than ~8h/day leads to build-up of neurobehavioral impairment across days. Although it is known that sleep loss effects depend on the circadian timing of sleep, it is not known how the timing of restricted sleep influences the accumulation of neurobehavioral impairment over days. Here we studied the accumulation of impairment across days of restricted sleep placed in the morning or afternoon. Methods N=71 healthy young adults (39% female; ages 21-45y, mean±SD: 27.9±6.6y) completed a 14-day laboratory study. After two baseline days with nighttime sleep (8h TIB: 23:30-07:30), subjects were randomized to 10 consecutive days of A) morning sleep at 4h, 6h, or 8h TIB ending at 11:30 each day (n=18, 8, 8, respectively), or B) afternoon sleep at 4h, 6h, or 8h TIB ending at 19:30 each day (n=13, 17, 7, respectively). Subjects were tested on the 10min psychomotor vigilance test (PVT) every ~2 hours during scheduled wakefulness. Daily averages for PVT lapses (RTs&amp;gt;500ms) observed between 2h and 14h after awakening were analyzed with non-linear mixed-effects regression to investigate differences in the neurobehavioral impairment build-up rate between sleep restriction conditions. Results Afternoon sleep conditions showed a significant sleep dose-response effect (p&amp;lt;0.001), with the fastest accrual of PVT performance deficits across days in the 4h condition, and slow-to-negligible accumulation (p=0.36) of PVT performance deficits in the 8h condition. However, morning sleep resulted in no significant sleep dose-response effect (p=0.96). All 3 morning sleep doses displayed negligible (p≥0.12) accumulation of impairment across days. Conclusion In this sample of young adults, sleep dosages ending in the morning (at 11:30) appear to provide considerable protection against cumulative performance deficits from sleep restricted to 4h-6h/day over 10 days, suggesting that the afternoon circadian promotion of wakefulness can sustain behavioral alertness even over multiple days of repeated sleep restriction. Support NIH grants R01-NR04281 and M01-RR00040

0779 Circadian Entrainment in 12h Night Shift Workers: The Environmental Lights Matter?

Abstract Introduction Shift workers frequently suffer sleep disturbance in relation with the atypical work schedules. In particular, night shift workers are exposed to inevitable sunlight or bright indoor lights during the morning hours that may disturb their daytime sleep. We aimed to find out the optimal environmental lights to facilitate circadian entrainment of 12h-shift workers by assessing melatonin profiles in the morning and daytime sleep quality. Methods We enrolled 12h-shift female nurses working at one hospital (n=10, mean age 29.4±3.5 years). The schedules of participants are identical such as day-day-night-night shifts and four consecutive off days. Participants admitted to the laboratory at 9:00 following 2nd night shift schedule. Saliva melatonin was taken six times every 30 minute from 10:00 to 12:30 under two different lighting conditions with organic light emitting diodes (OLED) or light emitting diodes (LED) with 150 lux of light intensity. Dim light condition (10 lux) was conducted as controls. Three sessions were randomly ordered with 8-10 days intervals. Participants were allowed to sleep after 12:30 with light off and woke up ad libitum. Results Melatonin concentration had decreased gradually from 10.6±11.4 to 5.0±8.2 pg/ml. Among three different lighting conditions, there were no statistical differences in salivary melatonin and sleep parameters recorded by polysomnography. Circadian entrainment in night shift workers was defined as that salivary melatonin concentration had maintained above 5 pg/ml at the time to bed. 20% of sessions (6/30) were classified as circadian entrainment (CE) and 80% (24/30) were as non-entrainment (NE). Mean melatonin concentration was 22.1±11.2 in CE and 3.9±4.1 pg/ml in NE (p&amp;lt;.001). CE showed significantly shorter sleep latency (0.5±0.3 vs. 1.5±1.4 min, p=.025) and wakefulness after sleep onset (13.6±6.3 vs. 27.9±16.8%, p=.015), and higher sleep efficiency (94.6±2.6 vs. 88.7±6.3%, p=.011) than NE. The number of each lighting condition was not different between CE and NE (p=.847). Conclusion This is a preliminary study with small number of participants. We found that environmental lights including dim light did not affect daytime sleep of 12h shift workers. Instead, daytime sleep quality was influenced by circadian entrainment with higher melatonin concentration in the morning. Support