Determinants of depressive mood in coronary artery disease patients with obstructive sleep apnea and response to continuous positive airway pressure treatment in non‐sleepy and sleepy phenotypes in the RICCADSA cohort

We explored determinants of depressive mood in adults with coronary artery disease and obstructive sleep apnea and response to positive airway pressure treatment in sleepy and non‐sleepy phenotypes. In this secondary analysis of the RICCADSA trial conducted in Sweden, 493 cardiac patients with obstructive sleep apnea (n = 386) or no obstructive sleep apnea (n = 107) with complete Epworth Sleepiness Scale and Zung Self‐rating Depression Scale questionnaires were included. Sleepy (Epworth Sleepiness Scale ≥10) versus non‐sleepy (Epworth Sleepiness Scale <10) patients with depressive mood (Zung Self‐rating Depression Scale score ≥50) were evaluated after 3 and 12 months of positive airway pressure treatment. In all, 133 patients (27.0%) had depressive mood (29.3% of obstructive sleep apnea versus 18.7% of no obstructive sleep apnea; p = 0.029), with a higher percentage among the sleepy phenotype (36.9% versus 24.5%; p = 0.009). In multivariate analysis, depressive mood was significantly associated with female sex, body mass index and Epworth Sleepiness Scale. Among 97 obstructive sleep apnea patients with depressive mood at baseline, there was a significant reduction in the scores at follow‐up both in the sleepy and non‐sleepy patients allocated to positive airway pressure treatment, whereas no significant changes were observed in the untreated group (p = 0.033). The device use (hr/night) predicted improvement in mood (odds ratio, 1.33; 95% confidence interval, 1.10–1.61; p = 0.003) adjusted for age, female sex, body mass index, left ventricular ejection fraction, apnea–hypopnea index and delta Epworth Sleepiness Scale score. We conclude that obstructive sleep apnea was associated with depressive mood in adults with coronary artery disease. Treatment with positive airway pressure improved mood in both phenotypes, independent of the confounding factors.     

Cardiovascular autonomic dysfunction in insomnia patients with objective short sleep duration

Two phenotypes have been proposed: insomnia with objective near‐normal sleep duration, related to increased psychological symptoms, and insomnia with objective short sleep duration, associated with cardiometabolic morbidity. Reduced heart rate variability has also been implicated in the pathophysiology of cardiometabolic disease; however, there are little data on whether cardiovascular function differs between patients with objective short sleep duration and near‐normal sleep duration. Participants (M_age = 49.9 ± 11.3 years; 62.8% female) were 180 adults with chronic insomnia (M_duration = 15.7 ± 13.6). Objective sleep duration was based on total sleep time averaged across two consecutive nights of polysomnography and subjective sleep duration was based on 2‐week sleep diaries. The sample was divided into two groups, with sleep duration shorter (polysomnography‐total sleep time: n = 46; sleep diary: n = 95) or equal/longer (polysomnography‐total sleep time: n = 134; sleep diary: n = 85) than 6 hr. Electrocardiogram data derived from polysomnography were used to obtain heart rate and heart rate variability during stage 2 (N2) and rapid eye movement sleep. Heart rate variability measures included absolute and normalized high‐frequency component, an index of parasympathetic activation, and the ratio of low‐ to high‐frequency (LF/HF ratio), an index of sympathovagal balance. After controlling for covariates (e.g., co‐morbidity), patients with objective short sleep duration had reduced high‐frequency (p < .05) and elevated low‐frequency/high‐frequency ratio (p = .036) and heart rate (p = .051) compared with patients with near‐normal sleep duration. No differences were observed between phenotypes when subjective sleep duration was used. Insomnia patients with objective short sleep duration showed significantly dampened parasympathetic activation and increased sympathovagal imbalance relative to their counterparts with near‐normal sleep duration. These findings highlight the importance of treating insomnia, as treatment may reduce the risk of cardiovascular disease.     

Effects of cumulative sleep restriction on self‐perceptions while multitasking

This study addressed a rarely studied question of self‐perceptions of performance and overall functional state during cumulative sleep restriction and the ensuing recovery period. Twenty healthy male volunteers, aged 19–29 years, were divided into a sleep restriction group (n = 13) and a control group (n = 7). On the first 2 nights, the sleep restriction group had an 8‐h sleep opportunity that was restricted to 4 h for the next 5 nights, and then restored to 8 h for the last 2 nights. The control group had an 8‐h sleep opportunity each night. Each day participants accomplished 50‐min multitask sessions and gave self‐ratings in their connection. Similar to our previous findings on multitasking performance, self‐perceived task performance, sleepiness and mental fatigue impaired during the sleep restriction and returned to baseline during the recovery phase. Self‐perceived mental effort, tension, task difficulty and task pace showed no sensitivity to the sleep restriction. We concluded that sleep‐restricted individuals can probably make use of some self‐perceptions when assessing their ‘fitness for duty’. However, at the individual level these measures seem to be inaccurate in revealing actual performance impairments.     

Disturbed sleep in attention‐deficit hyperactivity disorder (ADHD) is not a question of psychiatric comorbidity or ADHD presentation

Attention‐deficit hyperactivity disorder (ADHD) is a heterogeneous psychiatric disorder with three different presentations and high levels of psychiatric comorbidity. Serious sleep complaints are also common, but the role of the presentations and comorbidity in sleep is under‐investigated in ADHD. Consequently, the goal of the study was to investigate sleep problems in medicine‐naive school‐aged children (mean age = 9.6 years) with ADHD compared to controls using objective methods and to examine the role of comorbidity and presentations. Ambulatory polysomnography results suggested that children with ADHD (n = 76) had significantly more sleep disturbances than controls (n = 25), including a larger percentage of rapid eye movement (REM) sleep and more sleep cycles, as well as lower mean sleep efficiency, mean non‐REM (NREM) sleep stage 1 and mean NREM sleep stage 3. No significant between‐group differences were found on the multiple sleep latency test. Stratifying for comorbidity in the ADHD group did not reveal major differences between groups, but mean sleep latency was significantly longer in children with ADHD and no comorbidity compared to controls (36.1 min; SD = 30.1 versus 22.6 min; SD = 15.2). No differences were found between ADHD presentations. Our results support the presence of night‐time sleep disturbances in children with ADHD. Poor sleep does not appear to be attributable to comorbidity alone, nor do sleep disturbances differ within ADHD presentations.     

Effects of sleep on the realization of complex plans

Sleep consolidates newly encoded memories, particularly those memories that are relevant for future behaviour. This study explored whether sleep facilitates the successful execution of relatively complex plans in the future. We applied the Dresden Breakfast Task, in which subjects are instructed to prepare a virtual breakfast comprising several tasks (e.g. table‐setting, preparing eggs). After forming a detailed plan how to realize these tasks, the sleep group (n = 17) spent a night of sleep at home, monitored by polysomnography, and the wake group (n = 19) spent a normal day awake, monitored by actigraphy. After a 12‐h interval, all participants were asked to prepare the virtual breakfast. Contrary to our hypothesis, overall performance in breakfast preparation did not differ significantly between the sleep and wake groups. However, sleep participants performed better in one of six tasks, specifically the ‘table‐setting’ task (P < 0.01), which was driven by higher scores in a subtask measuring the correct position of the tableware (P < 0.01). Additional exploratory analyses revealed that a significant number of wake participants performed below the minimal score of the sleep group (P < 0.01) and sleep participants achieved the maximal score in significantly more subtasks than wake participants (57% versus 27%; P = 0.018). Plan adherence, assessing how well participants adhered to their own previously developed plan, did not differ between the sleep and wake groups. These findings provide the first evidence that sleep may support some aspects of the realization of complex, somewhat naturalistic plans .     

Mood impairment is stronger in young than in older adults after sleep deprivation

Sleep deprivation commonly impairs affective regulation and causes worse mood. However, the majority of previous research concerns young adults. Because susceptibility to sleep deprivation and emotion regulation change distinctively across adult age, we tested here the hypothesis that the effect of sleep deprivation on mood is stronger in young than in older adults. In an experimental design, young (18–30 years) and older adults (60–72 years) participated in either a sleep control (young, n = 63; older, n = 47) or a total sleep deprivation condition (young, n = 61; older, n = 47). Sleepiness, mood and common symptoms of sleep deprivation were measured using established questionnaires and ratings. Sleep‐deprived participants felt more sleepy, stressed and cold, and reported lower vigour and positive affect, regardless of age. All the other outcome measures (negative affect, depression, confusion, tension, anger, fatigue, total mood disturbance, hunger, cognitive attenuation, irritability) showed a weaker response to sleep deprivation in the older group, as indicated by age*sleep deprivation interactions (ps < 0.05). The results show that older adults are emotionally less affected by sleep deprivation than young adults. This tolerance was mainly related to an attenuated increase in negative mood. This could possibly be related to the well‐known positivity effect, which suggests that older adults prioritize regulating their emotions to optimize well‐being. The results also highlight that caution is warranted when generalizing results from sleep deprivation studies across the adult lifespan.     

Objectively measured night‐to‐night sleep variations are associated with body composition in very elderly women

This cross‐sectional study examined the association between objectively measured sleep patterns and body composition in very elderly community‐dwelling women. Participants included 191 community‐dwelling adults aged ≥ 80 years (mean age: 83.4 ± 2.6 years; age range: 80–92 years). Sleep and physical activity were monitored via accelerometer (ActiGraph GT3X+) during at least five consecutive 24‐h periods. Night‐to‐night sleep pattern variability across all nights of recording was assessed using standard deviations (SDs). Body composition was assessed using dual‐energy X‐ray absorptiometry. Simple and multivariable linear regression analyses were performed. The mean number of nights with usable actigraphy data was 7.3 ± 1.3. On average, participants went to bed at 22:57 hours (SD: 1.11 h) and rose from bed at 6:27 hours (SD: 1.01 h). Night‐to‐night bedtime, sleep duration and sleep timing mid‐point variations correlated slightly with the percentage body fat and percentage lean mass (P < 0.05). Multiple linear regression analysis revealed significant associations of night‐to‐night bedtime variations and inconsistent sleep–wake patterns with all body composition indices after adjusting for potential confounding factors, including mean nightly sleep duration, self‐reported nap duration and daily physical activity. After further adjusting for night‐to‐night wake time, sleep timing mid‐point and sleep duration variations, greater bedtime variability remained associated significantly with all body composition indices except lean/fat mass ratio. Inconsistent sleep–wake patterns were associated independently with an increased fat mass and decreased lean mass among very elderly women. These findings suggest that in most elderly individuals, sleep patterns might be an important modifiable factor associated with obesity and sarcopenia development.     

Age affects sleep microstructure more than sleep macrostructure

It is well known that the quantity and quality of physiological sleep changes across age. However, so far the effect of age on sleep microstructure has been mostly addressed in small samples. The current study examines the effect of age on several measures of sleep macro‐ and microstructure in 211 women (22–71 years old) of the ‘Sleep and Health in Women’ study for whom ambulatory polysomnography was registered. Older age was associated with significantly lower fast spindle (effect size f² = 0.32) and K‐complex density (f² = 0.19) during N2 sleep, as well as slow‐wave activity (log) in N3 sleep (f² = 0.21). Moreover, total sleep time (f² = 0.10), N3 sleep (min) (f² = 0.10), rapid eye movement sleep (min) (f² = 0.11) and sigma (log) (f² = 0.05) and slow‐wave activity (log) during non‐rapid eye movement sleep (f² = 0.09) were reduced, and N1 sleep (f² = 0.03) was increased in older age. No significant effects of age were observed on slow spindle density, rapid eye movement density and beta power (log) during non‐rapid eye movement sleep. In conclusion, effect sizes indicate that traditional sleep stage scoring may underestimate age‐related changes in sleep.     

Memory encoding is impaired after multiple nights of partial sleep restriction

Sleep is important for normative cognitive functioning. A single night of total sleep deprivation can reduce the capacity to encode new memories. However, it is unclear how sleep restriction during several consecutive nights affects memory encoding. To explore this, we employed a parallel‐group design with 59 adolescents randomized into sleep‐restricted (SR) and control groups. Both groups were afforded 9 h time in bed (TIB) for 2 baseline nights, followed by 5 consecutive nights of 5 h TIB for the SR group (n = 29) and 9 h TIB for the control group (n = 30). Participants then performed a picture‐encoding task. Encoding ability was measured with a recognition test after 3 nights of 9 h TIB recovery sleep for both groups, allowing the assessment of encoding ability without the confounding effects of fatigue at retrieval. Memory was significantly worse in the sleep‐restricted group (P = 0.001), and this impairment was not correlated with decline in vigilance. We conclude that memory‐encoding deteriorates after several nights of partial sleep restriction, and this typical pattern of sleep negatively affects adolescents’ ability to learn declarative information.     

Ecological momentary assessment of daytime symptoms during sleep restriction therapy for insomnia

This study profiles changes in self‐reported daytime functioning during sleep restriction therapy (SRT) for insomnia. Ecological momentary assessment (EMA) captured point‐in‐time symptomatology to map the time–course of symptoms. We hypothesized a deterioration (week 1) followed by improvements at week 3 of therapy relative to baseline. Nine patients with psychophysiological insomnia completed the Daytime Insomnia Symptom Scale (DISS) at rise‐time, 12:00 hours, 18:00 hours and bedtime for 1 week before and 3 weeks during SRT. Four validated factors from the DISS were analyzed (alert cognition, positive mood, negative mood and sleepiness/fatigue) across 28 days yielding 17 170 data points. Factors evaluated week (baseline versus weeks 1 and 3) and time of day symptomatology. Insomnia Severity Index scores decreased significantly pre‐to‐post treatment (mean 18 versus 7). Reflecting acute effects of SRT, significant differences were found for all factors, except negative mood, between baseline and week 1 of SRT, suggesting adverse effects. By week 3, sleepiness/fatigue and negative mood decreased significantly compared to baseline, and positive mood showed a trend towards improvement (P = 0.06). Sleepiness/fatigue displayed a significant week × time of day interaction, explained by a reduction in sleepiness/fatigue at every daytime assessment point (except bedtime, which remained high). A significant interaction for alert cognition was associated with reduction in alertness at bedtime by week 3 and an increase in alertness at rise‐time, suggesting that SRT not only improves sleep, but moderates alertness and sleepiness in therapeutic ways. Initial SRT is associated with an increase in sleepiness/fatigue and a decrease in alert cognition.     

Calibrating actigraphy to improve sleep efficiency estimates

Actigraphy (ACT) can enhance treatment for insomnia by providing objective estimates of sleep efficiency; however, only two studies have assessed the accuracy of actigraphy‐based estimates of sleep efficiency (ACT‐SE) in sleep‐disordered samples studied at home. Both found poor correspondence with polysomnography‐based estimates (PSG‐SE). The current study tested that concordance in a third sample and piloted a method for improving ACT‐SE. Participants in one of four diagnostic categories (panic disorder, post‐traumatic stress disorder, comorbid post‐traumatic stress and panic disorder and controls without sleep complaints) underwent in‐home recording of sleep using concurrent ambulatory PSG and actigraphy. Precisely synchronized PSG and ACT recordings were obtained from 41 participants. Sleep efficiency was scored independently using conventional methods, and ACT‐SE/PSG‐SE concordance examined. Next, ACT data recorded initially at 0.5 Hz were resampled to 30‐s epochs and rescaled on a per‐participant basis to yield optimized concordance between PSG‐ and ACT‐based sleep efficiency estimates. Using standard scoring of ACT, the correlation between ACT‐SE and PSG‐SE across participants was statistically significant (r = 0.35, P < 0.025), although ACT‐SE failed to replicate a main effect of diagnosis. Individualized calibration of ACT against a night of PSG yielded a significantly higher correlation between ACT‐SE and PSG‐SE (r = 0.65, P < 0.001; z = 1.692, P = 0.0452, one‐tailed) and a significant main effect of diagnosis that was highly correspondent with the effect on PSG‐SE. ACT‐based estimates of sleep efficiency in sleep‐disordered patients tested at home can be improved significantly by calibration against a single night of concurrent PSG.     

The effect of sleep deprivation on objective and subjective measures of facial appearance

The faces of people who are sleep deprived are perceived by others as looking paler, less healthy and less attractive compared to when well rested. However, there is little research using objective measures to investigate sleep‐loss‐related changes in facial appearance. We aimed to assess the effects of sleep deprivation on skin colour, eye openness, mouth curvature and periorbital darkness using objective measures, as well as to replicate previous findings for subjective ratings. We also investigated the extent to which these facial features predicted ratings of fatigue by others and could be used to classify the sleep condition of the person. Subjects (n = 181) were randomised to one night of total sleep deprivation or a night of normal sleep (8–9 hr in bed). The following day facial photographs were taken and, in a subset (n = 141), skin colour was measured using spectrophotometry. A separate set of participants (n = 63) later rated the photographs in terms of health, paleness and fatigue. The photographs were also digitally analysed with respect to eye openness, mouth curvature and periorbital darkness. The results showed that neither sleep deprivation nor the subjects’ sleepiness was related to differences in any facial variable. Similarly, there was no difference in subjective ratings between the groups. Decreased skin yellowness, less eye openness, downward mouth curvature and periorbital darkness all predicted increased fatigue ratings by others. However, the combination of appearance variables could not be accurately used to classify sleep condition. These findings have implications for both face‐to‐face and computerised visual assessment of sleep loss and fatigue.     

The impact of prolonged violent video‐gaming on adolescent sleep: an experimental study

Video‐gaming is an increasingly prevalent activity among children and adolescents that is known to influence several areas of emotional, cognitive and behavioural functioning. Currently there is insufficient experimental evidence about how extended video‐game play may affect adolescents' sleep. The aim of this study was to investigate the short‐term impact of adolescents' prolonged exposure to violent video‐gaming on sleep. Seventeen male adolescents (mean age = 16 ± 1 years) with no current sleep difficulties played a novel, fast‐paced, violent video‐game (50 or 150 min) before their usual bedtime on two different testing nights in a sleep laboratory. Objective (polysomnography‐measured sleep and heart rate) and subjective (single‐night sleep diary) measures were obtained to assess the arousing effects of prolonged gaming. Compared with regular gaming, prolonged gaming produced decreases in objective sleep efficiency (by 7 ± 2%, falling below 85%) and total sleep time (by 27 ± 12 min) that was contributed by a near‐moderate reduction in rapid eye movement sleep (Cohen's d = 0.48). Subjective sleep‐onset latency significantly increased by 17 ± 8 min, and there was a moderate reduction in self‐reported sleep quality after prolonged gaming (Cohen's d = 0.53). Heart rate did not differ significantly between video‐gaming conditions during pre‐sleep game‐play or the sleep‐onset phase. Results provide evidence that prolonged video‐gaming may cause clinically significant disruption to adolescent sleep, even when sleep after video‐gaming is initiated at normal bedtime. However, physiological arousal may not necessarily be the mechanism by which technology use affects sleep.     

Bedtime,shuteye time and electronic media: sleep displacement is a two‐step process

This study argues that going to bed may not be synonymous with going to sleep, and that this fragmentation of bedtime results in a two‐step sleep displacement. We separated bedtime (i.e. going to bed) from shuteye time (i.e. attempting to go to sleep once in bed) and assessed the prevalence of electronic media use in both time slots. A convenience sample of 338 adults (aged 18–25 years, 67.6% women) participated in an online survey. Results indicated a gap of 39 min between bedtime and shuteye time, referred to as ‘shuteye latency’. Respondents with a shuteye latency of, respectively, ≤30 min, ≤1 or >1 h, were 3.3, 6.1 and 9.3 times more likely to be rated as poor sleepers compared to those who went to sleep immediately after going to bed. Before bedtime, volume of electronic media use (17 h 55 min per week) was higher than non‐media activities (14 h per week), whereas the opposite was true after bedtime (media = 3 h 41 min, non‐media = 7 h 46 min). Shuteye latency was related exclusively to prebedtime media use. Findings confirmed the proposed fragmentation of bedtime. Sleep displacement should therefore be redefined as a two‐step process, as respondents not only engage in the delay of bedtime, but also in the delay of shuteye time once in bed. Theoretical, methodological and practical implications are discussed.     

Delay discounting and response disinhibition moderate associations between actigraphically measured sleep parameters and body mass index

Previous research suggests that the sleep–obesity association varies significantly across individuals. This study examined the associations between actigraphically measured sleep parameters and body mass index and hypothesized that the associations would be stronger in individuals with greater delay discounting, the devaluation of future rewards and response disinhibition and the difficulty in withholding previously rewarded responses. Seventy‐eight college students carried a wrist‐worn actigraph and completed diaries reporting bedtime, wake time and covariates including physical activity, alcohol and caffeine consumption, daytime nap duration and perceived stress for 7 days and completed the delay discounting and go/no‐go response disinhibition tasks. Their height and weight were measured. Only bedtime variability was significantly associated with body mass index in the main effect model controlling for all covariates (B = 0.03, P = 0.001). Delay discounting moderated associations of bedtime (B = 0.03, P < 0.001), sleep duration variability (B = 0.05, P = 0.002), bedtime variability (B = 0.03, P = 0.002) and wake time variability (B = 0.02, P < 0.001) with body mass index; these associations were significant only when the delay discounting rate was high. Response disinhibition moderated the association between bedtime variability and body mass index in a similar pattern (B = 0.01, P = 0.004). The findings suggest that, using actigraphy measures of sleep, circadian desynchrony rather than sleep duration is a risk factor for higher body mass index. The findings support the hypothesis that delay discounting and response disinhibition moderate the associations between sleep and body mass index. Delay discounting and response disinhibition might characterize individuals who are vulnerable to the influence of circadian desynchrony on weight.     

The relationship between a night's sleep and subsequent daytime functioning in older poor and good sleepers

Those suffering insomnia symptoms generally report daytime impairments. However, research has not assessed whether this relationship holds on a nightly basis, despite the strongly held belief that a night of poor sleep impairs mood and functioning the following day. The objective of this study was to test this relationship in a group of older poor sleepers with insomnia symptoms compared with good sleepers. This study utilized a within‐subjects design to investigate day‐to‐day subjective daytime functioning and its relation to the previous night's sleep. Seventeen older individuals (mean age: 67.5 years) were identified with a retrospective questionnaire and 2 weeks of sleep–wake diary to have poor sleep consistent with insomnia. Seventeen good sleepers (mean age: 67.8 years) were selected using the same measures. Participants reported their beliefs about sleep and daytime functioning on the Dysfunctional Beliefs and Attitudes about Sleep Scale (DBAS‐16). One week later they commenced a 14‐day period of sleep–wake diaries and concurrent responses to a modified Daytime Insomnia Symptom Scale (DISS). Results showed significant night‐to‐day covariation between sleep efficiency and daytime functioning for individuals with poor sleep (r = 0.34), but not for good sleepers (r = 0.08). Those poor sleepers who held this covariation belief most strongly were those who subsequently showed this night‐to‐day relationship the most strongly (r = 0.56). This was not true for good sleepers. For those suffering insomnia, these findings demonstrate their belief that a poor sleep is followed by an impaired daytime, consistent with their experience.     

The link between maternal sleep and permissive parenting during late adolescence

Utilizing a multi‐method design, the present study examined the association between maternal sleep, assessed via actigraphy and self‐reports, and permissive parenting (e.g. lax, inconsistent discipline) during adolescence, as well as the extent to which this association differed by mothers’ race/ethnicity and socioeconomic status. The sample was comprised of 234 mothers (M age = 41.76 years, SD = 6.25; 67% European‐American, 31% African‐American, 2% other race/ethnicities) and 237 adolescents (113 boys, 124 girls; M age = 15.80 years, SD = 0.80; 66% European‐American, 34% African‐American). Mothers’ sleep duration (actual sleep minutes) and quality (sleep efficiency, latency, long wake episodes) were assessed using actigraphy. Mothers also reported on their sleep problems and adolescents reported on mothers’ permissive parenting behaviours. Results revealed that actigraphy‐based longer sleep duration and shorter sleep latency were associated with lower levels of permissive parenting. Further, mothers’ race/ethnicity and socioeconomic status moderated the association between actigraphy‐based sleep quality (i.e. sleep efficiency, long wake episodes) and permissive parenting. Specifically, a negative association between sleep efficiency and permissive parenting was evident only for African‐American mothers. In addition, a positive association between more frequent night wakings and permissive parenting was evident only for mothers from lower socioeconomic status households. The findings highlight the benefits of longer and higher‐quality sleep for reducing the risk of permissive parenting, especially among ethnic minority mothers and mothers from lower socioeconomic status households.     

Gross motor adaptation benefits from sleep after training

Sleep has been shown to facilitate the consolidation of newly acquired motor memories. However, the role of sleep in gross motor learning, especially in motor adaptation, is less clear. Thus, we investigated the effects of nocturnal sleep on the performance of a gross motor adaptation task, i.e. riding an inverse steering bicycle. Twenty‐six male participants (M = 24.19, SD = 3.70 years) were randomly assigned to a PM‐AM‐PM (n = 13) or an AM‐PM‐AM (n = 13) group, i.e. they trained in the evening/morning and were re‐tested the next morning/evening and the following evening/morning (PM‐AM‐PM/AM‐PM‐AM group) so that every participant spent one sleep as well as one wake interval between the three test sessions. Inverse cycling performance was assessed by speed (riding time) and accuracy (standard deviation of steering angle) measures. Behavioural results showed that in the PM‐AM‐PM group a night of sleep right after training stabilized performance (accuracy and speed) and was further improved over the subsequent wake interval. In the AM‐PM‐AM group, a significant performance deterioration after the initial wake interval was followed by the restoration of subjects' performance levels from right after training when a full night of sleep was granted. Regarding sleep, right hemispheric fast N2 sleep spindle activity was related to better stabilization of inverse cycling skills, thus possibly reflecting the ongoing process of updating the participants' mental model from “how to ride a bicycle” to “how to ride an inverse steering bicycle”. Our results demonstrate that sleep facilitates the consolidation of gross motor adaptation, thus adding further insights to the role of sleep for tasks with real‐life relevance.     

Integrating nap and night‐time sleep into sleep patterns reveals differential links to health‐relevant outcomes

Both night‐time sleep and nap behaviour have been linked consistently to health outcomes. Although reasons for napping are usually tied to night‐time sleep, the majority of studies assess their effects independently. The current study thus aimed to examine the health relevance of patterns of sleep behaviour that take into account both night‐time and daytime sleep habits. Night‐time sleep, recorded during 7 days via actigraphy from 313 participants (aged 34–82 years) of the Midlife in the United States II Biomarker study, was assessed. Blood and urine specimens were assayed for noradrenaline, interleukin‐6 and C‐reactive protein. Participants self‐reported nap behaviour, depressive symptoms, perceived chronic stress and the presence of medical symptoms and conditions. Overall, nappers (n = 208) showed elevated waist–hip ratios, C‐reactive protein and interleukin‐6 levels compared to non‐nappers and reported more physiological symptoms and conditions (all P ≤ 0.019). Within nappers, cluster analysis revealed three patterns of sleep behaviour—infrequent nappers with good night‐time sleep, frequent nappers with good night‐time sleep and nappers with poor night‐time sleep. Nappers with poor night‐time sleep thereby exhibited elevated noradrenaline levels, depressive symptoms and perceived stress scores compared to other groups (all P ≤ 0.041). These findings support the idea that nap–health relationships are complex, in that frequency of napping and accumulation of nap sleep is not related linearly to health consequences. Assessing nap behaviour in conjunction with night‐time sleep behaviour appeared crucial to elucidate further the health relevance of napping, particularly in terms of psychological health outcomes, including chronic stress and depressive symptoms.     

Comparison of sleep structure and psychometric profiles in patients with fibromyalgia,osteoarthritis and healthy controls

While research indicates that both the macro‐ and microstructure of sleep may be altered in fibromyalgia syndrome, few studies have controlled for symptom duration or included pain‐control participants (i.e. patients with chronic pain and sleep disturbance not associated with fibromyalgia syndrome). A frequently reported alteration found in the sleep microstructure of patients with fibromyalgia syndrome is the alpha‐delta sleep anomaly. Although alpha waves have been observed during N3 sleep in healthy individuals, it has been proposed that there is an increase in alpha wave activity during slow‐wave sleep in fibromyalgia syndrome. Originally considered a possible neurological contribution to fibromyalgia syndrome, whether the alpha‐delta sleep anomaly is fundamental to the development of fibromyalgia syndrome, or results mainly from the pain experience remains unknown. The present study was designed to compare sleep macro‐ and microstructure, and psychometric profiles, in three broadly age‐matched groups of female participants: patients with fibromyalgia syndrome (n = 19); patients with osteoarthritis with sleep disturbance (n = 17); and healthy adults (n = 10). Patients with fibromyalgia syndrome met the American College of Rheumatology diagnostic criteria and were recruited within 6 months of diagnosis. Subjective sleep quality was significantly lowest, and levels of anxiety and depressive symptoms were significantly highest for patients with fibromyalgia syndrome. However, the groups showed no significant differences in polysomnographic measures of total sleep time, sleep latency and total wake after sleep onset. Levels of alpha‐delta sleep were statistically similar in both clinical (fibromyalgia syndrome and osteoarthritis) groups, indicating that it is not a specific abnormality of fibromyalgia syndrome. Overall, subjective measurements of anxiety, depression, fatigue and sleep quality better discriminated between the three groups than did objective measurements of sleep variables.