Subsequent Night Research Articles

The effect of replacing prolonged sitting with intermittent standing during a simulated workday on the subsequent night’s sleep

The effect of replacing prolonged sitting with intermittent standing during a simulated workday on the subsequent night’s sleep

Modafinil Subjectively Does Not Impair Sleep in Aviators After a Period of Extended Wakefulness.

INTRODUCTION: Modafinil is used as a countermeasure to limit the effects of fatigue in military aviation. However, literature is conflicting about its negative effects on subsequent sleep.METHODS: This randomized placebo-controlled trial conducted by the Center of Man in Aviation of the Royal Netherlands Airforce is part of a larger study. It included 32 subjects (mean age 35 yr old, 84% male) who followed a normal daily routine and stayed awake the subsequent night. At midnight, all subjects received either 300 mg caffeine, 200 mg modafinil, or placebo. At the end of the test night, subjects were awake for a median period of 26 h. Afterwards, sleep questionnaires containing qualitative (Groningen Sleep Quality Scale) and quantitative parameters of sleep for the subsequent day (recovery sleep) and consecutive night (post-test sleep) were completed and statistically analyzed using Friedman and Wilcoxon signed rank tests.RESULTS: A statistically significant difference in the reported recovery sleep was observed. The modafinil group slept 30% shorter than placebo, but sleep efficiency was not statistically different. Quantitatively post-test sleep did not vary statistically significantly between the three groups. However, Groningen Sleep Quality Scale scores were lower post-test than pre-test in the modafinil group, while this was not the case in the caffeine and placebo group.DISCUSSION:This study found that modafinil subjectively does not negatively impact recovery sleep or subsequent nighttime sleep after an extended period of wakefulness and suggests it may decrease the need for recovery sleep compared to placebo or caffeine.Wingelaar-Jagt YQ, Wingelaar TT, Riedel WJ, Ramaekers JG. Modafinil subjectively does not impair sleep in aviators after a period of extended wakefulness. Aerosp Med Hum Perform. 2024; 95(6):290-296.

0874 Impact of Physical Activity on Subsequent Night's Sleep in Patients After Cardiac Surgery

0874 Impact of Physical Activity on Subsequent Night's Sleep in Patients After Cardiac Surgery

Maternal Circadian Disruption from Shift Work and the Impact on the Concentration of Melatonin in Breast Milk.

Background and Objective: Melatonin in breast milk exhibits a 24-hour circadian rhythm, present in nighttime breast milk but nearly undetectable in daytime breast milk. Shift work can disrupt the circadian timing of individuals, evident in changes in melatonin in saliva and urine samples. However, it is unknown whether these changes are also reflected in breast milk from a shift working mother. The aim of this study was to investigate whether maternal circadian rhythm disturbance from shift work impacts the melatonin concentration in breast milk. Materials and Methods: Breast milk and saliva samples were collected from 11 shift working mothers at four timepoints across five consecutive days. This included during their day shift or nonworkdays to act as a control, night shift, subsequent night shifts and postnight shift. Where possible, pre- and postfeed collections were also undertaken. Samples were grouped into four-time intervals: 12-6:30 am, 7-11:30 am, 12-6:30 pm, 7-11:30 pm, and melatonin levels (picogram per milliliter) in the breast milk and saliva samples were analyzed. Results: There was a significant decrease in breast milk melatonin (p = 0.026) at the 12-6:30 am time interval on subsequent night shifts, compared with control days. However, there was no overall time and shift type interaction effect (p = 0.70). In addition, no observed difference in melatonin levels was found in saliva samples, or when comparing pre- and postfeed breast milk. Breast milk melatonin however was found to be significantly higher compared with saliva (p > 0.001), at all but one time interval. Conclusion: The findings suggest that there is a potential effect of maternal circadian rhythm disruption from shift work on breast milk melatonin levels. This is an important step in exploring the role of maternal circadian timing and the effect on breast milk composition. Expansion of this research and exploration of other circadian rhythm misalignment sleep disorders on breast milk is highly recommended.

Directional associations among real-time activity, sleep, mood, and daytime symptoms in major depressive disorder using actigraphy and ecological momentary assessment

Previous research has suggested that individuals with major depressive disorder (MDD) experienced alterations in sleep and activity levels. However, the temporal associations among sleep, activity levels, mood, and daytime symptoms in MDD have not been fully investigated. The present study aimed to fill this gap by utilizing real-time data collected across time points and days. 75 individuals with MDD and 75 age- and gender-matched healthy controls were recruited. Ecological momentary assessments (EMA) were adopted to assess real-time mood status for 7 days, and actigraphy was employed to measure day-to-day sleep-activity patterns. Multilevel modeling analyses were performed. Results revealed a bidirectional association between mood/daytime symptoms and activity levels across EMA intervals. Increased activity levels were predictive of higher alert cognition and positive mood, while an increase in positive mood also predicted more increase in activity levels in depressed individuals. A bidirectional association between sleep and daytime symptoms was also found. Alert cognition was found to be predictive of better sleep in the subsequent night. Contrariwise, higher sleep efficiency predicted improved alert cognition and sleepiness/fatigue the next day. A unidirectional association between sleep and activity levels suggested that higher daytime activity levels predicted a larger increase in sleep efficiency among depressed individuals. This study indicated how mood, activity levels, and sleep were temporally and intricately linked to each other in depressed individuals using actigraphy and EMA. It could pave the way for novel and efficacious treatments for depression that target not just mood but sleep and activity levels.

Hit the gym or hit the hay: can evening exercise characteristics predict compromised sleep in healthy adults?

Introduction: Recent sleep guidelines regarding evening exercise have shifted from a conservative (i.e., do not exercise in the evening) to a more nuanced approach (i.e., exercise may not be detrimental to sleep in circumstances). With the increasing popularity of wearable technology, information regarding exercise and sleep are readily available to the general public. There is potential for these data to aid sleep recommendations within and across different population cohorts. Therefore, the aim of this study was to examine if sleep, exercise, and individual characteristics can be used to predict whether evening exercise will compromise sleep. Methods: Data regarding evening exercise and the subsequent night's sleep were obtained from 5,250 participants (1,321F, 3,929M, aged 30.1 ± 5.2yrs) using a wearable device (WHOOP 3.0). Data for females and males were analysed separately. The female and male datasets were both randomly split into subsets of training and testing data (training:testing = 75:25). Algorithms were trained to identify compromised sleep (i.e., sleep efficiency <90%) for females and males based on factors including the intensity, duration and timing of evening exercise. Results: When subsequently evaluated using the independent testing datasets, the algorithms had sensitivity for compromised sleep of 87% for females and 90% for males, specificity of 29% for females and 20% for males, positive predictive value of 32% for females and 36% for males, and negative predictive value of 85% for females and 79% for males. If these results generalise, applying the current algorithms would allow females to exercise on ~ 25% of evenings with ~ 15% of those sleeps being compromised and allow males to exercise on ~ 17% of evenings with ~ 21% of those sleeps being compromised. Discussion: The main finding of this study was that the models were able to predict a high percentage of nights with compromised sleep based on individual characteristics, exercise characteristics and habitual sleep characteristics. If the benefits of exercising in the evening outweigh the costs of compromising sleep on some of the nights when exercise is undertaken, then the application of the current algorithms could be considered a viable alternative to generalised sleep hygiene guidelines.

No effects of different modalities of a single bout of exercise on sleep architecture and appetite in healthy overweight or obese young adults

BackgroundStudies on the effect of acute exercise on sleep quality and quantity reported contradictory results and the bulk of these studies were conducted in lean individuals. Furthermore, not many studies have assessed subsequent changes in appetite following an acute bout of exercise. Therefore, the exact effect of aerobic acute exercise on sleep parameters in overweight/obese young adults remains unclear. As such, the purpose of this study was to investigate the effects of a single bout of aerobic exercise on sleep architecture in healthy, overweight/obese, young adults. MethodsEighteen participants (50% female; mean age 21±1 year) with no self-reported sleep disorders or chronic health conditions took part in this study. The Balke-Ware procedure (treadmill-graded test) was used to determine exhaustion peak oxygen consumption (VO2peak). The intervention consisted of three conditions (no exercise, moderate, and intensive). Heart rates corresponding to 50% and 75% VO2peak were used to establish work rates for moderate and intense exercise conditions, respectively. Following each intervention, sleep parameters were measured throughout the night using polysomnography. Additionally, participants completed appetite visual analogue scales before each meal, on the day of the exercise, and the following day. ResultsUnivariable analyses did not yield significant results between the independent variables (condition, order, and sex) and sleep parameters; however, the intense condition (normalised to the moderate condition) had a positive relationship with the number of arousals during the subsequent night. No significant effects were noted for the multivariate analysis. Further, there was no global effect of order (p = 0.651), sex (p = 0.628), and appetite time (p = 0.400) and individual sleep characteristics did not have an effect on the Hunger and Fullness scales. However, the percentage of stage 2 had a positive effect on the Quantity scale, and the amount and percentage of time spent in REM had a negative effect on the Quantity scale, but multivariable analyses were not significant. ConclusionAcute aerobic exercise (intense or moderate) does not have beneficial or adverse effects on sleep quality and quantity in young adults with overweight/obesity. Subjective appetite may have a relationship with REM and stage 2 sleep independent of exercise.

A Study on REM Sleep Homeostasis in the Day-Active Tree Shrew (Tupaia belangeri): Cold-Induced Suppression of REM Sleep Is Not Followed by a Rebound.

The function and regulation of rapid-eye-movement (REM) sleep is a topic of ongoing debate. It is often assumed that REM sleep is a homeostatically regulated process and that a need for REM sleep builds up, either during prior wakefulness or during preceding slow wave sleep. In the current study, we tested this hypothesis in six diurnal tree shrews (Tupaia belangeri), small mammals closely related to primates. All animals were individually housed and kept under a 12:12 light-dark cycle with an ambient temperature of 24 °C. We recorded sleep and temperature in the tree shrews for 3 consecutive 24 h days. During the second night, we exposed the animals to a low ambient temperature of 4 °C, a procedure that is known to suppress REM sleep. Cold exposure caused a significant drop in brain temperature and body temperature and also resulted in a strong and selective suppression of REM sleep by 64.9%. However, contrary to our expectation, the loss of REM sleep was not recovered during the subsequent day and night. These findings in a diurnal mammal confirm that the expression of REM sleep is highly sensitive to environmental temperature but do not support the view that REM sleep is homeostatically regulated in this species.

Abstract MP46: Higher Daytime Fruit, Vegetable, and Carbohydrate Intake is Associated With Less Fragmented Nighttime Sleep in Adults With Adequate Sleep Duration

Introduction: Population studies show an association between higher quality diets and better sleep quality. Some clinical intervention studies have supported an influence of diet on sleep but have primarily examined specific foods and not complete dietary patterns. In a previous study, we showed that higher intakes of fiber and lower intakes of sugar and saturated fat were associated with deeper, less disrupted sleep. However, this was examined over a single day and night. In this study, we used multiple days of dietary records and sleep, assessed by actigraphy, to determine the temporal associations between dietary intakes during the day and sleep on the subsequent night. Hypothesis: We hypothesized that consumption of a diet higher in fruits, vegetables, nuts and seeds, and whole grains, components of a Mediterranean diet, would predict better sleep quality. Methods: We examined habitual sleep patterns and self-reported diet in 34 adults (28 men and 6 women, 50% racial/ethnic minority, age: 28±7 years, BMI: 19.8-33.7 kg/m 2 ) who participated in 2 separate studies aimed at assessing the influence of diet and meal timing on sleep and energy balance. Diet was assessed using the Automated Self-Administered 24-hour (ASA-24) Dietary Assessment Tool. Sleep during the subsequent night was assessed using wrist actigraphy. Participants provided an average of 6.0±1.5 d of diet and accompanying sleep data. Sleep quality was estimated using the sleep fragmentation index (SFI), a measure of sleep disruption, expressed as the ratio of the number of awakenings to the total sleep time in minutes. Linear mixed effects models were used to examine the relationship between dietary intakes during the day and sleep fragmentation during the subsequent night. Models were adjusted for age, sex, BMI, and total energy intake. Results: On average, participants consumed 2085±743 kcal, 94±43 g protein, 84±38 g fat, 233±89 g carbohydrate, 21±11 g fiber, 329±154 mg magnesium, 3±2 cups fruits and vegetables, 1±2 oz nuts/seeds, and 8±7 tsp added sugar per day. Average total sleep time and sleep efficiency were 423±70 min and 89±6%, respectively; SFI was 17±9. Consumption of more fruits and vegetables (β(SE)=-0.60(0.29), P=0.04) and carbohydrates (β(SE)=-0.02(0.007), P=0.02) was associated with lower SFI, indicative of less disrupted sleep, during the subsequent night. Also, trends for inverse associations with SFI were observed for fiber (β(SE)=-0.1(0.06), P=0.08), magnesium (β(SE)=-0.007(0.004), P=0.09), and vegetable intake (β(SE)=-0.72(0.39), P=0.07). Conclusion: In adequate sleepers, consumption of a diet higher in fruits, vegetables, carbohydrates, fiber, and magnesium, was associated with less fragmented sleep. These results suggest that diets rich in these nutrients, such as the Mediterranean and DASH diets, might play a role in promoting better sleep quality. Future intervention studies are warranted.

Advantage conferred by overnight sleep on schema-related memory may last only a day.

Sleep contributes to declarative memory consolidation. Independently, schemas benefit memory. Here we investigated how sleep compared with active wake benefits schema consolidation 12 and 24 hours after initial learning. Fifty-three adolescents (age: 15-19 years) randomly assigned into sleep and active wake groups participated in a schema-learning protocol based on transitive inference (i.e. If B > C and C > D then B > D). Participants were tested immediately after learning and following 12-, and 24-hour intervals of wake or sleep for both the adjacent (e.g. B-C, C-D; relational memory) and inference pairs: (e.g.: B-D, B-E, and C-E). Memory performance following the respective 12- and 24-hour intervals were analyzed using a mixed ANOVA with schema (schema, no-schema) as the within-participant factor, and condition (sleep, wake) as the between-participant factor. Twelve hours after learning, there were significant main effects of condition (sleep, wake) and schema, as well as a significant interaction, whereby schema-related memory was significantly better in the sleep condition compared to wake. Higher sleep spindle density was most consistently associated with greater overnight schema-related memory benefit. After 24 hours, the memory advantage of initial sleep was diminished. Overnight sleep preferentially benefits schema-related memory consolidation following initial learning compared with active wake, but this advantage may be eroded after a subsequent night of sleep. This is possibly due to delayed consolidation that might occur during subsequent sleep opportunities in the wake group. Name: Investigating Preferred Nap Schedules for Adolescents (NFS5) URL: https://clinicaltrials.gov/ct2/show/NCT04044885. Registration: NCT04044885.

How Sleep Affects Recovery and Performance in Basketball: A Systematic Review.

Sleep is considered an essential component related to physiological and psychological recovery in athletes and particularly in basketball, given the impact of condensed travel and game schedules on player health and performance. The aim of this systematic review is to examine studies published to date on sleep and basketball performance. All scientific articles that reported a relationship between sleep and its possible impact on performance in basketball are included. The research processes followed the PRISMA criteria, and the relevant articles were extracted (PubMed, WOS, Scopus) as of December 31, 2021. Twenty-eight articles were selected for inclusion and data extraction, with 27 demonstrating that sleep is a vital component in the recovery of basketball players and their corresponding on-court performance. Three central themes that we identified: (1) the quality and extension of sleep (the better quality and more extension of sleep, better performance and lower probability of injury); (2) influence of the players circadian rhythm (travel and game scheduling do not currently facilitate or take this into account); and (3) higher training loads and/or increased stress may jeopardize a subsequent good night's sleep, which should be taken into account when scheduling practices and workouts. The current systematic review regarding sleep and basketball performance and highlights that there is a strong relationship between both variables. Collectively, the evidence supports the critical influence of sleep on player recovery and basketball performance and risk for injury.

The Effects of Recovery Sleep on Experimental Pain

Recent research suggests that recovery sleep (RS) has the potential to restore pain sensitivity and modulation after hyperalgesia due to preceding sleep deprivation. However, it has not yet been systematically examined whether the restoration of these pain parameters is driven by sleep characteristics of RS. Thus, the present study assessed changes in experimental pain during RS after total sleep deprivation (TSD) to test whether RS parameters predicted the restoration of the pain system. Thirty healthy participants completed one night of habitual sleep, one night of TSD and a subsequent recovery night. At-home sleep during baseline and recovery was assessed using portable polysomnography and a questionnaire. Before and after each night pressure pain thresholds (PPTs), temporal pain summation (TSP) and conditioned pain modulation (CPM) were assessed. PPTs decreased after TSD and increased following RS, indicating a restoration of pain sensitivity after hyperalgesia. RS characteristics did not predict this restoration, suggesting other mechanisms (eg, changes in serotonergic activity) underlying the observed pain changes. TSP indicated a lack of effect of experimental sleep manipulations on excitatory processes whereas CPM lacked sufficient reliability to investigate inhibitory processes. Thus, results indicate moderate effects of sleep manipulations on pain sensitivity, but not on pain modulation. PerspectiveThis article highlights the potential of recovery sleep to let pain thresholds return to normal following their decrease after a night of total sleep deprivation. In contrast, endogenous pain modulation (temporal pain summation, conditioned pain modulation) was not affected by sleep deprivation and recovery sleep.

Sleep and physical activity – the dynamics of bi-directional influences over a fortnight

Study objectivesThe day-to-next day predictions between physical activity (PA) and sleep are not well known, although they are crucial for advancing public health by delivering valid sleep and physical activity recommendations. We used Big Data to examine cross-lagged time-series of sleep and PA over 14 days and nights.MethodsBi-directional cross-lagged autoregressive pathways over 153,154 days and nights from 12,638 Polar watch users aged 18–60 years (M = 40.1 SD = 10.1; 44.5% female) were analyzed with cross-lagged panel data modeling (RI-CPL). We tested the effects of moderate-to-vigorous physical activity (MVPA) vs. high intensity PA (vigorous, VPA) on sleep duration and quality, and vice versa.ResultsWithin-subject results showed that more minutes spent in VPA the previous day was associated with shorter sleep duration the next night, whereas no effect was observed for MVPA. Longer sleep duration the previous night was associated with less MVPA but more VPA the next day. Neither MVPA nor VPA were associated with subsequent night’s sleep quality, but better quality of sleep predicted more MVPA and VPA the next day.ConclusionsSleep duration and PA are bi-directionally linked, but only for vigorous physical activity. More time spent in VPA shortens sleep the next night, yet longer sleep duration increases VPA the next day. The results imply that a 24-h framing for the interrelations of sleep and physical activity is not sufficient – the dynamics can even extend beyond, and are activated specifically for the links between sleep duration and vigorous activity. The results challenge the view that sleep quality can be improved by increasing the amount of PA. Yet, better sleep quality can result in more PA the next day.

0236 The First Night Effect In Adolescents With And Without Insomnia

Abstract Introduction Insomnia in adolescence is a common and debilitating condition, and vulnerability to stress is known to play a major role its development. In this study, we investigated the effects of sleeping under stress in a sample of adolescents with and without clinically significant insomnia symptoms. The first night in the laboratory was used as an established experimental paradigm for eliciting stress through exposure to an unfamiliar environment. Methods Forty-one postpubertal adolescents (18.4 ± 0.7 years) with (n=14, 9 girls) and without (n=27, 16 girls) DSM-5 insomnia symptoms completed two non-consecutive polysomnographic (PSG) nights in the laboratory. Repeated-measures ANOVAs were used to analyze differences in PSG sleep measures between the first and subsequent night, with group (insomnia vs. control) and sex as between-subject factors. Results Both groups showed a robust stress effect on the first night, characterized by lower sleep efficiency (↓2.2%) and total sleep time (↓6.4%), and more awakenings (↑12.4%) compared with the subsequent night (p&amp;lt;0.05). Both groups also had less non-rapid-eye-movement (NREM) (↓4.9%) and REM (↓18.8%) sleep on the first night. Girls with insomnia had lower amounts of REM sleep than boys with insomnia on both nights (p&amp;lt;0.05). Both groups perceived higher levels of pre-sleep somatic (↑10.3%) and total (↑7.2%) arousal on the first night compared to the subsequent night (p&amp;lt;0.05). For cognitive arousal, there was a night-group-sex interaction effect: while controls showed no changes between the two nights, boys with insomnia reported significantly lower pre-sleep cognitive arousal levels on the subsequent laboratory night compared to the first night (↓32.9%), whereas cognitive arousal levels remained elevated on the subsequent night in girls with insomnia (p&amp;lt;0.05). Conclusion Sleeping for the first time in the laboratory leads to greater pre-sleep arousal and disrupts sleep in adolescents with and without insomnia symptoms. Longitudinal studies are needed to examine the female vulnerability in the manifestation of stress-related hyperarousal, particularly in the context of insomnia development during adolescence. Support (If Any) This study was supported by the National Heart, Lung and Blood Institute (NHLBI) grant R01 HL139652 (MdZ). The content is solely the responsibility of the authors and does not necessarily represent the official views the National Institutes of Health.

0805 Halo-Traction induced Obstructive sleep apnea

Abstract Introduction Obstructive sleep apnea (OSA) is the most common sleep-related breathing disorder. It is a multi-factorial disease with a variety of identified causes including age, male gender, obesity, craniofacial and upper airway abnormalities. We would like to describe a patient who had severe OSA following application of Halo traction, which significantly improved following the removal of the device. Report of Cases: 14-year-old male with medical history of spina bifida, chiari malformation s/p decompression, shunted hydrocephalus and severe scoliosis, was admitted to the hospital for anterior spinal discectomy L2-S1 and Halo application with traction for scoliosis. He previously had nocturnal polysomnogram (NPSG) in 2017 that demonstrated very mild mixed apnea with an apnea hypopnea index (AHI) of 5.5. Because central apneas were very brief and clustered in REM, family elected to repeat a study rather than treat. In 2019, he had a follow up study with complaints of snoring and thirst, and this demonstrated an AHI of 21 with 29 brief central apneas and 72 hypopneas, 1 obstructive apnea. He had a T&amp;A and turbinate ablation and due to the global pandemic did not undergo repeat sleep study. During admission for his anterior spinal discectomy and Halo, he demonstrated persistent night time hypoxia. A split night sleep study showed evidence of severe OSA with pretreatment AHI of 94.4, oxygen nadir 86%. Continuous positive airway pressure (CPAP) was initiated at 5 cm of water and titrated to 11 cm of water. On CPAP of +11 severe obstructive events continued with an AHI of 40.6, oxygen nadir 92%. A bilevel positive airway pressure (BIPAP) titration study the subsequent night started at pressures of 12/6 and titrated to 21/9 with respiratory rate of 12 yet demonstrated AHI of 51, oxygen nadir 89%. Study transitioned to average volume assisted pressure support (AVAPS) with IPAP max of 26, IPAP minimum of 12 EPAP of 9, tidal volume of 175ml, rate of 12 with inadequate control of his obstructive events with an AHI of 24.8, minimum oxygen saturations of 91. While hospitalized, he remained on AVAPS with normal capillary blood gases. Halo traction was removed 2 weeks following his surgery with plan was to send him home on AVAPS and repeat NPSG in 6 weeks. However, as a result of COVID pandemic/Philips recall, CPAP was the only device available for home use, so CPAP therapy at +8 cm was trialed overnight, demonstrating oxygen nadir of 92% and a normal capillary blood gas in the morning. Patient was then discharged home on CPAP of +8 cm of water. He returned back to sleep center for a BIPAP titration study to re-establish BIPAP/AVAPS settings, as his inpatient sleep study had shown severe OSA. During the sleep study, he was started on BIPAP 12/6 and he remained on it throughout the night with 0 central and 0 obstructive events. As he did well, he was advised to continue CPAP +8 with plans to repeat the sleep study off CPAP. In clinic follow up, he reported mild skin breakdown and occasionally waking unrefreshed. Conclusion As our patient did significantly better following the removal of Halo traction device, it is likely that Halo traction device caused fixed over flexion of the cervical spine that resulted in decrease in his airway diameter, which further worsened during his sleep, and caused severe OSA. Support (If Any)

Methamphetamine-Induced Sleep Impairments and Subsequent Slow-Wave and Rapid Eye Movement Sleep Rebound in Male Rhesus Monkeys.

Use of amphetamine-type stimulants is associated with numerous adverse health outcomes, with disturbed sleep being one of the most prominent consequences of methamphetamine use. However, the extent to which methamphetamine alters sleep architecture, and whether methamphetamine-induced sleep impairment is associated with next-day sleep rebound effects, has received relatively little investigation. In the present study, we investigated the effects of acute morning methamphetamine administration on sleep parameters in adult male rhesus monkeys (N = 4) using a fully-implantable telemetry system. Monkeys were prepared with telemetry devices that continuously monitored electroencephalography (EEG), electromyography (EMG) and electrooculography (EOG) throughout the night. We investigated the effects of morning (10h00) administration of methamphetamine (0.01–0.3 mg/kg, i.m.) on sleep during the night of the injection. In addition, we investigated sleep during the subsequent night in order to assess the possible emergence of sleep rebound effects. Methamphetamine administration dose-dependently increased sleep latency and wake time after sleep onset (WASO). Methamphetamine also decreased total sleep time, which was reflected by a decrease in total time spent in N2, slow-wave (N3) and REM sleep stages, while increasing the percentage of total sleep time spent in sleep stage N1. Importantly, methamphetamine decreased time spent in N3 and REM sleep even at doses that did not significantly decrease total sleep time. Sleep rebound effects were observed on the second night after methamphetamine administration, with increased total sleep time reflected by a selective increase in time spent in sleep stages N3 and REM, as well as a decrease in REM sleep latency. Our findings show that methamphetamine administered 8 h prior to the inactive (dark) phase induces marked changes in sleep architecture in rhesus monkeys, even at doses that do not change sleep duration, and that sleep rebound effects are observed the following day for both N3 and REM sleep stages.

Self-Conscious Affect Is Modulated by Rapid Eye Movement Sleep but Not by Targeted Memory Reactivation–A Pilot Study

The neurophysiological properties of rapid eye movement sleep (REMS) are believed to tune down stressor-related emotional responses. While prior experimental findings are controversial, evidence suggests that affective habituation is hindered if REMS is fragmented. To elucidate the topic, we evoked self-conscious negative affect in the participants (N = 32) by exposing them to their own out-of-tune singing in the evening. Affective response to the stressor was measured with skin conductance response and subjectively reported embarrassment. To address possible inter-individual variance toward the stressor, we measured the shame-proneness of participants with an established questionnaire. The stressor was paired with a sound cue to pilot a targeted memory reactivation (TMR) protocol during the subsequent night's sleep. The sample was divided into three conditions: control (no TMR), TMR during slow-wave sleep, and TMR during REMS. We found that pre- to post-sleep change in affective response was not influenced by TMR. However, REMS percentage was associated negatively with overnight skin conductance response habituation, especially in those individuals whose REMS was fragmented. Moreover, shame-proneness interacted with REM fragmentation such that the higher the shame-proneness, the more the affective habituation was dependent on non-fragmented REMS. In summary, the potential of REMS in affective processing may depend on the quality of REMS as well as on individual vulnerability toward the stressor type.

Assessment of effects of total sleep deprivation and subsequent recovery sleep: a methodological strategy feasible without sleep laboratory

BackgroundSleep is critical for maintaining homeostasis in bodily and neurobehavioral functions. This homeostasis can be disturbed by sleep interruption and restored to normal by subsequent recovery sleep. Most research regarding recovery sleep (RS) effects has been conducted in specialized sleep laboratories, whereas small, less-well equipped research units may lack the possibilities to run studies in this area. Hence, the aims of the present study were to develop and validate an experimental protocol, which allows a thorough assessment of at-home recovery sleep after sleep deprivation.MethodsThe experimental protocol, comprising one night of baseline sleep (BL) at home, one night of monitored total sleep deprivation and a subsequent recovery night at home, was tested in a sample of 30 healthy participants. Subjects’ fatigue and alertness were assessed prior to and after each night. Sleep at home (BL, RS) was objectively assessed using portable polysomnography. To check whether our at-home sleep assessments yielded results that are comparable to those conducted in sleep laboratories, we compared the sleep data assessed in our study with sleep data assessed in laboratory studies.ResultsSleep parameters assessed during RS exhibited changes as expected (prolonged total sleep time, better sleep efficiency, slow wave sleep rebound). Sleep parameters of BL and RS were in line with parameters assessed in previous studies examining sleep in a laboratory setting. Fatigue normalized after one night of RS; alertness partly recovered.ConclusionsOur results suggest a successful implementation of our new experimental protocol, emphasizing it as a useful tool for future studies on RS outside of well-equipped sleep laboratories.

Shorter Sleep Predicts Longer Subsequent Day Sedentary Duration in Healthy Midlife Adults, but Not in Those with Sleep Apnea.

PurposeSedentary behavior and suboptimal sleep increase risks for chronic diseases. We hypothesized that sedentary behavior and sleep affect each other and that an underlying sleep disorder would alter these relationships. To test these hypotheses, we studied the bidirectional relationships between sedentary behavior and sleep (duration and efficiency) in healthy controls (HC) and people with untreated obstructive sleep apnea (OSA).Patients and MethodsFifty-two volunteers (18 HC, 19 mild OSA [apnea/hypopnea index [AHI] range 5–14.9/hour], 15 moderate OSA [AHI range 15–29.9/hour]) were studied with actigraphy and sleep diaries across ~9 consecutive nights of self-selected consistent ~8-hour sleep episodes at home (range 4–21/nights per person). We analyzed whether total time asleep and sleep efficiency affected the subsequent daytime sedentary duration while controlling for body mass index and whether the severity of OSA altered this relationship. We also tested the reverse relationship, namely whether daytime sedentary duration affected the subsequent night’s sleep and if any such relationship differed with OSA severity.ResultsOvernight sleep duration and efficiency negatively predicted the subsequent day’s sedentary duration in HC (p<0.02), but not in people with mild or moderate OSA (p>0.05). There was no significant reverse relationship between daytime sedentary duration and the subsequent night’s sleep duration or efficiency (p≥0.2).ConclusionIn healthy adults, short nighttime sleep predicts a longer duration of sedentary behavior on a subsequent day, but we did not observe this relationship in people with OSA. The mechanisms underlying this association in healthy individuals and its disruption in the presence of OSA need to be studied.

The acute effects of aerobic exercise on sleep in patients with unipolar depression: a randomized controlled trial.

Study ObjectivesInsomnia increases the risk of negative disease trajectory, relapse, and suicide in patients with depression. We aimed at investigating the effects of a single bout of aerobic exercise, performed after 02:00 pm, on the subsequent night’s sleep in patients with depression.MethodsThe study was designed as a two-arm parallel-group, randomized, outcome assessor-blinded, controlled, superiority trial. Patients between 18 and 65 years of age with a primary diagnosis of unipolar depression were included. The intervention was a single 30-minute bout of moderate aerobic exercise. The control group sat and read for 30 minutes. The primary outcome was sleep efficiency measured by polysomnography. Secondary outcomes were other polysomnographic variables, subjective sleep quality, daytime sleepiness, mood states, and adverse events.ResultsNinety-two patients were randomized to the exercise (N = 46) or control group (N = 46). There were no clinically relevant differences at baseline. Intent-to-treat analysis ANCOVA of follow-up sleep efficiency, adjusted for baseline levels and minimization factors, did not detect a significant effect of the allocation (β = −0.93, p = 0.59). There was no evidence for significant differences between both groups in any other objective or subjective sleep outcomes, daytime sleepiness, or adverse events. The intervention had an immediate positive effect on mood states, including depressiveness (β = −0.40, p = 0.003).ConclusionsThis is the first trial to study the effects of a single bout of aerobic exercise on sleep in patients with depression to the best of our knowledge. Aerobic exercise had no effect on sleep efficiency but had a strong beneficial effect on mood and did not increase adverse outcomes. These results add to the growing body of evidence that, contrary to sleep hygiene recommendations, exercise after 02:00 pm is not detrimental for sleep.Clinical Trial RegistrationClinicaltrials.gov, https://clinicaltrials.gov/ct2/show/NCT03673397. Protocol registered on September 17, 2018.