Disrupted rapid eye movement sleep predicts poor declarative memory performance in post‐traumatic stress disorder

Successful memory consolidation during sleep depends on healthy slow‐wave and rapid eye movement sleep, and on successful transition across sleep stages. In post‐traumatic stress disorder, sleep is disrupted and memory is impaired, but relations between these two variables in the psychiatric condition remain unexplored. We examined whether disrupted sleep, and consequent disrupted memory consolidation, is a mechanism underlying declarative memory deficits in post‐traumatic stress disorder. We recruited three matched groups of participants: post‐traumatic stress disorder (n = 16); trauma‐exposed non‐post‐traumatic stress disorder (n = 15); and healthy control (n = 14). They completed memory tasks before and after 8 h of sleep. We measured sleep variables using sleep‐adapted electroencephalography. Post‐traumatic stress disorder‐diagnosed participants experienced significantly less sleep efficiency and rapid eye movement sleep percentage, and experienced more awakenings and wake percentage in the second half of the night than did participants in the other two groups. After sleep, post‐traumatic stress disorder‐diagnosed participants retained significantly less information on a declarative memory task than controls. Rapid eye movement percentage, wake percentage and sleep efficiency correlated with retention of information over the night. Furthermore, lower rapid eye movement percentage predicted poorer retention in post‐traumatic stress disorder‐diagnosed individuals. Our results suggest that declarative memory consolidation is disrupted during sleep in post‐traumatic stress disorder. These data are consistent with theories suggesting that sleep benefits memory consolidation via predictable neurobiological mechanisms, and that rapid eye movement disruption is more than a symptom of post‐traumatic stress disorder.     

Subjective–objective sleep discrepancy among older adults: associations with insomnia diagnosis and insomnia treatment

Discrepancy between subjective and objective measures of sleep is associated with insomnia and increasing age. Cognitive behavioural therapy for insomnia improves sleep quality and decreases subjective–objective sleep discrepancy. This study describes differences between older adults with insomnia and controls in sleep discrepancy, and tests the hypothesis that reduced sleep discrepancy following cognitive behavioural therapy for insomnia correlates with the magnitude of symptom improvement reported by older adults with insomnia. Participants were 63 adults >60 years of age with insomnia, and 51 controls. At baseline, participants completed sleep diaries for 7 days while wearing wrist actigraphs. After receiving cognitive behavioural therapy for insomnia, insomnia patients repeated this sleep assessment. Sleep discrepancy variables were calculated by subtracting actigraphic sleep onset latency and wake after sleep onset from respective self‐reported estimates, pre‐ and post‐treatment. Mean level and night‐to‐night variability in sleep discrepancy were investigated. Baseline sleep discrepancies were compared between groups. Pre–post‐treatment changes in Insomnia Severity Index score and sleep discrepancy variables were investigated within older adults with insomnia. Sleep discrepancy was significantly greater and more variable across nights in older adults with insomnia than controls, P ≤ 0.001 for all. Treatment with cognitive behavioural therapy for insomnia was associated with significant reduction in the Insomnia Severity Index score that correlated with changes in mean level and night‐to‐night variability in wake after sleep onset discrepancy, P < 0.001 for all. Study of sleep discrepancy patterns may guide more targeted treatments for late‐life insomnia.     

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.     

Worried sleep: 24-h monitoring in high and low worriers

Background

Commonly used trait measures might not accurately capture the relationship between worry and sleep difficulties in real life.

Methods

In a 24-h ambulatory monitoring study, high and low trait worriers maintained a log of worry and sleep characteristics while actigraphy, heart rates (HR), skin conductance (SC), and ambient temperature were recorded.

Results

Worrying in bed on the night of the recording was associated with longer self-reported and actigraphic nocturnal awakenings, lower actigraphic sleep efficiency, higher HR, lower HR variability, elevated SC level, and more non-specific SC fluctuations compared to not worrying in bed. High trait worriers had higher HR during waking and sleep, and reported shorter total sleep time and poorer sleep quality.

Conclusions

While trait worry is mainly associated with subjective sleep difficulties, worrying in bed impairs sleep according to both subjective and objective sleep parameters, including heightened sympathetic and reduced parasympathetic activation.     

The effect on sleep of being on‐call: an experimental field study

The aim of this study was to: (i) gain more insight into the relationship between being on‐call and sleep and (ii) investigate the role of stress in this relationship. Data were collected by means of an experimental field study with a within‐subject design (two conditions, random order). Ninety‐six students participated during two consecutive nights: a reference night and a simulated on‐call night without an actual call. Participants were told they could be called at any time during the on‐call night. In the case of a call, participants had to perform online tasks for approximately 30 min. Self‐reported sleep quality and the extent to which participants experienced stress during the on‐call period were assessed by means of short questionnaires. Actigraphy was used to obtain objective sleep measures. Results for actigraphy data revealed no significant within‐person differences between conditions. However, participants reported longer sleep onset latencies, more awakenings and more wake after sleep onset during the on‐call night than during the reference night. They also reported more sleep problems and a lower overall sleep quality, and felt less recuperated after the on‐call night. Perceived stress moderated the relationship between being on‐call, on one hand, and the number of awakenings, wake after sleep onset, sleep problems and overall sleep quality, on the other hand. Results show that, even in the absence of an actual call, sleep during on‐call nights is of lower quality and has less restorative value – especially when being on‐call is experienced as stressful.     

Disturbed sleep and activity in toddlers with early signs of attention deficit hyperactivity disorder (ADHD)

This study investigated whether early signs of attention deficit hyperactivity disorder (ADHD) in toddlers aged 2–3 years are associated with disturbed sleep and activity levels. Participants were recruited from the Odense Child Cohort, and children scoring above the 93^rd percentile on the ADHD scale of the Child Behaviour Checklist 1½–5 were categorised as cases and compared with age‐ and gender‐matched normal‐scoring controls. Daytime and nocturnal activity for 24 children with ADHD traits (cases) and 25 healthy controls was assessed through 7 days of actigraphy, and parents completed the Children's Sleep Habits Questionnaire (CSHQ) and the ADHD Rating Scale IV Preschool Version (ADHD‐RS). Cases differed significantly on actigraphic parameters by having fewer minutes of moderate‐to‐vigorous physical activity (MVPA), prolonged total sleep time, fewer sleep interruptions, and increased night‐to‐night variability. A significant association was found between fewer minutes of MVPA and higher parent‐reported motor activity on the ADHD‐RS. Furthermore, increased night‐to‐night variability was significantly associated with higher total scores on both CSHQ and ADHD‐RS. The findings show that early signs of ADHD are associated with an irregular sleep pattern and lower daytime activity, as illustrated by actigraphy. Studies investigating early ADHD risk factors could lead to a preschool ADHD risk index to help guide future early intervention.     

Sleep among primary care physicians–Association with overtime,night duties and strategies to counteract poor sleep quality

Physicians belong to the risk group for sleep disorders as a result of work related stress, excessive working time, large amount of on‐call duties and shift work. Poor sleep quality of healthcare providers threatens not only their safety, but also the safety of their patients. This study examines if there are any differences in how working either long hours or at night duties relates to self‐reported sleep time, sleep quality and daytime sleepiness in primary care physicians. We analyzed data from a survey research of 807 participants. Respondents were divided into four groups based on their reported work hours per week and number of nights on duty per month. Overtime was associated with shorter sleep time and worse subjective sleep quality even when compared with that of participants who work on night duties. All investigated groups of participants reported short sleep latencies which suggests that sleep debt is a common problem in this population. Surprisingly in the case of poor sleep quality participants rarely used recommended methods like regular physical activity or specialist advice. The most frequently reported answer was that they do nothing to improve sleep and every third participants uses hypnotics to do that. These results suggest that primary care physicians despite being at high risk for sleep disorders due to working overtime and at night, pay less attention to their sleep quality and do not use recommended strategies to improve it.     

Integrative body–mind–spirit intervention for concurrent sleep and mood disturbances: sleep‐specific daytime functioning mediates sleep and mood improvements

Sleep disturbances and depressive symptoms are associated closely with daytime dysfunctions, yet few studies have investigated their temporal relationship in a randomized controlled trial. We investigated the inter‐relationships among sleep, depressive symptoms and daytime functioning following an integrative body–mind–spirit (I‐BMS) intervention. One hundred and eighty‐five participants (mean age 55.28 years, 75.1% female) with co‐existing sleep and depressive symptoms were randomized to I‐BMS or waiting‐list. Daytime functioning variables included the daytime dysfunction items of the Pittsburg Sleep Quality Index (PSQI‐day), Somatic Symptom Inventory, Hospital Anxiety Depression Scale and Short Form Health Survey collected at baseline, post‐treatment and 3‐month follow‐up. Sleep and depressive symptoms were measured by the sleep items of the PSQI (PSQI‐night) and Center for Epidemiological Studies Depression Scale (excluding the sleep item) (CESD‐M). Regression and path analyses were used to understand the role of daytime functioning in sleep and depressive symptoms. We found significant group and time effects on almost all daytime variables and significant group × time interactions on PSQI‐day and somatic symptoms. The adjusted regression model showed that CESD‐M was associated with all daytime variables. However, PSQI‐night was associated only with PSQI‐day. Path analyses indicated that PSQI‐day bridged PSQI‐night and CESD‐M in a two‐way direction after the I‐BMS intervention. The conclusion was that, following I‐BMS intervention, improvement in daytime functioning was related predominantly to improvement in depressive symptoms. Night‐time sleep related only to daytime dysfunction that was specific to sleep disturbances. Therefore, ‘sleep‐specific daytime impairment’ could be regarded as a major link from night‐time sleep to depressive symptoms. More studies are required to understand the concept of ‘sleep‐specific daytime impairment’.     

Exercise before bed does not impact sleep inertia in young healthy males

Sleep inertia is the transitional state marked by impaired cognitive performance and reduced vigilance upon waking. Exercising before bed may increase the amount of slow‐wave sleep within the sleep period, which has previously been associated with increased sleep inertia. Healthy males (n = 12) spent 3 nights in a sleep laboratory (1‐night washout period between each night) and completed one of the three conditions on each visit – no exercise, aerobic exercise (30 min cycling at 75% heart rate), and resistance exercise (six resistance exercises, three sets of 10 repetitions). The exercise conditions were completed 90 min prior to bed. Sleep was measured using polysomnography. Upon waking, participants completed five test batteries every 15 min, including the Karolinska Sleepiness Scale, a Psychomotor Vigilance Task, and the Spatial Configuration Task. Two separate linear mixed‐effects models were used to assess: (a) the impact of condition; and (b) the amount of slow‐wave sleep, on sleep inertia. There were no significant differences in sleep inertia between conditions, likely as a result of the similar sleep amount, sleep structure and time of awakening between conditions. The amount of slow‐wave sleep impacted fastest 10% reciprocal reaction time on the Psychomotor Vigilance Task only, whereby more slow‐wave sleep improved performance; however, the magnitude of this relationship was small. Results from this study suggest that exercise performed 90 min before bed does not negatively impact on sleep inertia. Future studies should investigate the impact of exercise intensity, duration and timing on sleep and subsequent sleep inertia.     

CBT for late‐life insomnia and the accuracy of sleep and wake perceptions: Results from a randomized‐controlled trial

Subjective and objective estimates of sleep are often discordant among individuals with insomnia who typically under‐report sleep time and over‐report wake time at night. This study examined the impact and durability of cognitive‐behavioural therapy for insomnia on improving the accuracy of sleep and wake perceptions in older adults, and tested whether changes in sleep quality were related to changes in the accuracy of sleep/wake perceptions. One‐hundred and fifty‐nine older veterans (97% male, mean age 72.2 years) who met diagnostic criteria for insomnia disorder were randomized to: (1) cognitive‐behavioural therapy for insomnia (n = 106); or (2) attention control (n = 53). Assessments were conducted at baseline, post‐treatment, 6‐months and 12‐months follow‐up. Sleep measures included objective (via wrist actigraphy) and subjective (via self‐report diary) total sleep time and total wake time, along with Pittsburgh Sleep Quality Index score. Discrepancy was computed as the difference between objective and subjective estimates of wake and sleep. Minutes of discrepancy were compared between groups across time, as were the relationships between Pittsburgh Sleep Quality Index scores and subsequent changes in discrepancy. Compared with controls, participants randomized to cognitive‐behavioural therapy for insomnia became more accurate (i.e. minutes discrepancy was reduced) in their perceptions of sleep/wake at post‐treatment, 6‐months and 12‐months follow‐up (p < .05). Improved Pittsburgh Sleep Quality Index scores at each study assessment preceded and predicted reduced discrepancy at the next study assessment (p < .05). Cognitive‐behavioural therapy for insomnia reduces sleep/wake discrepancy among older adults with insomnia. The reductions may be driven by improvements in sleep quality. Improving sleep quality appears to be a viable path to improving sleep perception and may contribute to the underlying effectiveness of cognitive‐behavioural therapy for insomnia.     

The sleep of remitted bipolar outpatients: a controlled naturalistic study using actigraphy

Background: Several sleep laboratory studies suggest sleep abnormalities in bipolar disorder. However, this is the first study to compare remitted bipolar subjects with controls on actigraphic and subjective sleep parameters in a naturalistic setting over 5 nights. Methods: Nineteen subjects with Bipolar I Disorder and 19 age- and gender-matched healthy controls were included. Objective sleep parameters were estimated using wrist actigraphs. Subject-rated sleep diaries and mood ratings were also completed. Sleep data were averaged for each subject across nights, and raw score standard deviations were calculated as a measure of within-subject variability. Results: Multivariate analyses of variance found significant group differences for both actigraphic (F(4,33)=3.80, P=0.012) and subjective measures (F(4,31)=3.18, P=0.027). Univariate analyses identified reliable differences in sleep onset latency (subjective), sleep duration (subjective), and variability of sleep duration and night wake time (actigraphic). Binary backward stepwise logistic regression demonstrated that a combination of three sleep measures correctly predicted disorder status in 84% of cases. Limitations: Failure to match on sociodemographic and employment status is a limitation that may provide an alternative explanation for some findings. Furthermore, in the bipolar group 18 of 19 subjects were in receipt of psychotropic medication, compared to none of the healthy control group. Also, no information was recorded about family history of mental disorders in the control group. Conclusions: The study suggests that the sleep of remitted bipolar outpatients measured in naturalistic settings is characteristically different from controls: bipolar subjects sleep longer, report longer onset latencies, and display greater variability across nights.     

Sex differences in objective measures of sleep in post‐traumatic stress disorder and healthy control subjects

A growing literature shows prominent sex effects for risk for post‐traumatic stress disorder and associated medical comorbid burden. Previous research indicates that post‐traumatic stress disorder is associated with reduced slow wave sleep, which may have implications for overall health, and abnormalities in rapid eye movement sleep, which have been implicated in specific post‐traumatic stress disorder symptoms, but most research has been conducted in male subjects. We therefore sought to compare objective measures of sleep in male and female post‐traumatic stress disorder subjects with age‐ and sex‐matched control subjects. We used a cross‐sectional, 2 × 2 design (post‐traumatic stress disorder/control × female/male) involving83 medically healthy, non‐medicated adults aged 19–39 years in the inpatient sleep laboratory. Visual electroencephalographic analysis demonstrated that post‐traumatic stress disorder was associated with lower slow wave sleep duration (F_(3,82) = 7.63, P = 0.007) and slow wave sleep percentage (F_(3,82) = 6.11, P = 0.016). There was also a group × sex interaction effect for rapid eye movement sleep duration (F_(3,82) = 4.08, P = 0.047) and rapid eye movement sleep percentage (F_(3,82) = 4.30, P = 0.041), explained by greater rapid eye movement sleep in post‐traumatic stress disorder females compared to control females, a difference not seen in male subjects. Quantitative electroencephalography analysis demonstrated that post‐traumatic stress disorder was associated with lower energy in the delta spectrum (F_(3,82) = 6.79, P = 0.011) in non‐rapid eye movement sleep. Slow wave sleep and delta findings were more pronounced in males. Removal of post‐traumatic stress disorder subjects with comorbid major depressive disorder, who had greater post‐traumatic stress disorder severity, strengthened delta effects but reduced rapid eye movement effects to non‐significance. These findings support previous evidence that post‐traumatic stress disorder is associated with impairment in the homeostatic function of sleep, especially in men with the disorder. These findings suggest that group × sex interaction effects on rapid eye movement may occur with more severe post‐traumatic stress disorder or with post‐traumatic stress disorder comorbid with major depressive disorder.     

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.     

Sleep of primary enuretic children and controls

STUDY OBJECTIVES: To look for differences between the sleep of enuretic children and controls. DESIGN: In addition to standard polysomnographic features, body movement data and nocturnal micturitions were recorded. SETTING: The children's homes. PARTICIPANTS: Twenty-one children with primary nocturnal enuresis and 6 controls of similar age. INTERVENTIONS: None. RESULTS: Sleep of the enuretic children did not diverge to a large extent from that of the controls. The only significant differences were that the enuretic children spent a slightly longer time in bed and had an increased number of sleep cycles. Although there was a trend for an increased number of short movements in enuretics, this was not statistically significant. Fifteen children experienced enuresis during the recording night. Micturition occurred during the first half of the night for most of the children and was not linked to any specific sleep stage. Children who voided during rapid-eye movemnt (REM) sleep were found to have more REM sleep than the others. Tachycardia was often seen to precede the enuretic event. In some subjects a short EEG arousal was observed before micturition. CONCLUSIONS: Sleep of enuretic children is polysomnographically normal, but the children exhibit signs of autonomous arousal prior to micturition.     

Adverse childhood experiences associated with sleep in primary insomnia

The objectives were to explore the association between self-reported adverse childhood experiences (ACE) and sleep in adults suffering from primary insomnia and to examine the impact of presleep stress on this relationship. Fifty-nine patients with primary insomnia, aged 21-55 years, were administered the Childhood Trauma Questionnaire (CTQ) and then divided into two groups according to the achieved scores: with moderate/severe or low/no reports of ACE. The participants spent three consecutive nights in the sleep laboratory in order to record polysomnographic and actigraphic sleep parameters. A stress induction technique was administered by activating negative autobiographical memories immediately before sleep in the second or third night. Results show that 46% of the insomniac patients reported moderate to severe ACE. This group exhibited a significantly greater number of awakenings and more movement arousals compared to patients with low or no reports of ACE. Actigraphic data also indicated more disturbed sleep and increased nocturnal activity for the high-ACE group. On the other hand, no specific group differences were found with regard to stress condition. The results support the assumption that it is possible to identify a subgroup among patients with primary insomnia who has experienced severe maltreatment in childhood and adolescence. This subgroup appears to differ in several sleep parameters, indicating a more disturbed sleep compared to primary insomniacs with low or no reports of ACE. With regard to sleep-disturbing nightly patterns of arousal, parallels between individuals with high ACE and trauma victims as well as post-traumatic stress disorder-patients suggest themselves.     

Adaptation effects to sleep studies in participants with and without chronic posttraumatic stress disorder

The “first night effect” (FNE) is the alteration of sleep architecture observed on the first night of polysomnographic (PSG) studies. It is unclear whether the FNE reflects adaptation to the equipment, sleeping environment, or both. Moreover, it is possible that certain patient populations, such as those with posttraumatic stress disorder (PTSD), demonstrate greater adaptation effects that are highly context dependent. We assessed FNE in participants with PTSD and healthy controls in a cross‐sectional study consisting of PSG testing at home and in the hospital. Contrary to our expectations, the PTSD group showed no adaptation effects in either setting. Only the control group assigned to the “hospital first” condition showed significant decreases in total sleep time on night 1 versus night 2 of the study. The results suggest that the FNE is related to adaptation to the combination of the hospital environment and the recording equipment.     

Actigraphy validation with insomnia

STUDY OBJECTIVE: Actigraphy, a method of inferring sleep from the presence or absence of wrist movement, has been well validated against polysomnography in trials with people without insomnia. However, the small amount of literature on validation with insomniacs has revealed an actigraphy bias toward overscoring sleep. The current validation trial with insomniacs used the largest number of subjects to date in such research and attracted participants with diverse demographic characteristics. DESIGN: People with insomnia slept 1 night in the laboratory while simultaneously being monitored by polysomnography, actigraphy (high-sensitivity algorithm of the Mini Mitter AW64 Actiwatch), and morning sleep diary. SETTING: Sleep disorders center. PARTICIPANTS: Participants were 57 volunteers from the community, 26 men and 31 women, ranging in age from 21 to 87 years. All participants satisfied conservative criteria for insomnia. The sample included subjects with primary insomnia, subjects with comorbid insomnia, and hypnotic users with current insomnia complaints. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: Actigraphy was successfully validated on 4 measures of sleep pattern--number of awakenings, wake time after sleep onset, total sleep time, and sleep efficiency percentage--based on nonsignificant mean differences and significant correlation between actigraphy and polysomnography. Sleep-onset latency with actigraphy was not significantly different from polysomnography but was weakly correlated with polysomnography. Hypnotic use contributed to actigraphic overscoring of sleep. CONCLUSIONS: Actigraphy proved to be a satisfactory objective measure of sleep on 4 of 5 sleep parameters, but these results are specific to this particular instrument using this particular algorithm and should not be construed as a blanket endorsement of actigraphy for measuring insomnia.     

Time in bed,sleep quality and associations with cardiometabolic markers in children: the Prevention and Incidence of Asthma and Mite Allergy birth cohort study

We investigated associations of time in bed and multiple sleep quality characteristics with cardiometabolic markers in children. Data from the prevention and incidence of asthma and mite allergy study, a population‐based prospective birth‐cohort study started in 1996–1997 in the Netherlands, were analysed. In total 1481 children aged 11–12 years completed a questionnaire (including questions on sleep) and underwent a medical examination. We measured body mass index, waist circumference, total‐ and high‐density lipoprotein cholesterol, blood pressure and glycated haemoglobin. Results showed that in girls, some sleep characteristics were related to anthropometrics (body mass index, waist circumference) and cholesterol. Girls who had a long time in bed (11–12.5 h) had 0.16 lower body mass index z‐score (95% confidence interval ?0.31; ?0.01) and 0.99 cm smaller waist circumference (95% confidence interval ?2.01; ?0.13) compared with girls who spent 10–10.5 h in bed. Girls who went to bed late and rose early had 0.16 mm higher total cholesterol (95% confidence interval 0.01; 0.31) and 0.08 mm higher high‐density lipoprotein cholesterol (95% confidence interval 0.01; 0.14) than ‘early to bed/early rise’ girls. Girls with night‐time awakenings had 0.14 mm higher total cholesterol (95% confidence interval 0.03; 0.25) than girls without night‐time awakenings. Girls who felt sleepy/tired ≥1 day per week had 0.10 mm lower high‐density lipoprotein cholesterol (95% confidence interval ?0.16; ?0.04) and 0.17 mm higher total cholesterol/high‐density lipoprotein cholesterol ratio (95% confidence interval 0.02; 0.32) than girls who did not feel sleepy. No associations were found for boys. Sleep characteristics were not related to blood pressure and glycated haemoglobin, and effect sizes of the associations in girls were small. Therefore, we consider it premature to propose that improved sleep could reduce cardiovascular risk during childhood.     

Excessive daytime sleepiness associated with insufficient sleep

Chronic insufficient sleep as an identifiable cause of excessive daytime sleepiness was investigated post hoc by comparing a series of patients with this diagnosis with patients with narcolepsy. Among the prominent features differentiating patients with insufficient sleep from patients with narcolepsy was the report, obtained on the sleep history, of a disparity between the reported amount of sleep obtained on weekdays versus weekends. On evaluation in the laboratory, patients with insufficient sleep showed atypically high sleep efficiency at night and a prolonged sleep time (longer than they report sleeping on a weekday night at home). Compared with patients with narcolepsy, they show a somewhat elevated percentage of stage 3-4 and REM sleep, although this is probably not higher than that of age-matched controls. On the Multiple Sleep Latency Test they displayed moderate sleepiness and no sleep onset REM periods. A mental status examination and Minnesota Multiphasic Personality Inventory did not suggest a primary psychiatric disorder.     

Actigraphy in studies on insomnia: Worth the effort?

In the past decades, actigraphy has emerged as a promising, cost-effective, and easy-to-use tool for ambulatory sleep recording. Polysomnography (PSG) validation studies showed that actigraphic sleep estimates fare relatively well in healthy sleepers. Additionally, round-the-clock actigraphy recording has been used to study circadian rhythms in various populations. To this date, however, there is little evidence that the diagnosis, monitoring, or treatment of insomnia can significantly benefit from actigraphy recordings. Using a case–control design, we therefore critically examined whether mean or within-subject variability of actigraphy sleep estimates or circadian patterns add to the understanding of sleep complaints in insomnia. We acquired actigraphy recordings and sleep diaries of 37 controls and 167 patients with varying degrees of insomnia severity for up to 9 consecutive days in their home environment. Additionally, the participants spent one night in the laboratory, where actigraphy was recorded alongside PSG to check whether sleep, in principle, is well estimated. Despite moderate to strong agreement between actigraphy and PSG sleep scoring in the laboratory, ambulatory actigraphic estimates of average sleep and circadian rhythm variables failed to successfully differentiate patients with insomnia from controls in the home environment. Only total sleep time differed between the groups. Additionally, within-subject variability of sleep efficiency and wake after sleep onset was higher in patients. Insomnia research may therefore benefit from shifting attention from average sleep variables to day-to-day variability or from the development of non-motor home-assessed indicators of sleep quality.