Estimating sleep parameters using an accelerometer without sleep diary.

Wrist worn raw-data accelerometers are used increasingly in large-scale population research. We examined whether sleep parameters can be estimated from these data in the absence of sleep diaries. Our heuristic algorithm uses the variance in estimated z-axis angle and makes basic assumptions about sleep interruptions. Detected sleep period time window (SPT-window) was compared against sleep diary in 3752 participants (range = 60-82 years) and polysomnography in sleep clinic patients (N = 28) and in healthy good sleepers (N = 22). The SPT-window derived from the algorithm was 10.9 and 2.9 minutes longer compared with sleep diary in men and women, respectively. Mean C-statistic to detect the SPT-window compared to polysomnography was 0.86 and 0.83 in clinic-based and healthy sleepers, respectively. We demonstrated the accuracy of our algorithm to detect the SPT-window. The value of this algorithm lies in studies such as UK Biobank where a sleep diary was not used.

Novel loci associated with usual sleep duration: the CHARGE Consortium Genome-Wide Association Study.

Usual sleep duration is a heritable trait correlated with psychiatric morbidity, cardiometabolic disease and mortality, although little is known about the genetic variants influencing this trait. A genome-wide association study (GWAS) of usual sleep duration was conducted using 18 population-based cohorts totaling 47 180 individuals of European ancestry. Genome-wide significant association was identified at two loci. The strongest is located on chromosome 2, in an intergenic region 35- to 80-kb upstream from the thyroid-specific transcription factor PAX8 (lowest P=1.1 × 10(-9)). This finding was replicated in an African-American sample of 4771 individuals (lowest P=9.3 × 10(-4)). The strongest combined association was at rs1823125 (P=1.5 × 10(-10), minor allele frequency 0.26 in the discovery sample, 0.12 in the replication sample), with each copy of the minor allele associated with a sleep duration 3.1 min longer per night. The alleles associated with longer sleep duration were associated in previous GWAS with a more favorable metabolic profile and a lower risk of attention deficit hyperactivity disorder. Understanding the mechanisms underlying these associations may help elucidate biological mechanisms influencing sleep duration and its association with psychiatric, metabolic and cardiovascular disease.

Sleep and daily functioning during androgen deprivation therapy for prostate cancer.

A limited body of evidence suggests that sleep problems are common in prostate cancer patients undergoing androgen deprivation therapy, yet little is known about sleep characteristics and the effects of poor sleep on daily functioning in this population. This study assessed sleep in 60 prostate cancer patients taking androgen deprivation therapy with wrist actigraphy and daily diaries for 7 days. The Epworth Sleepiness Scale and the general version of the Functional Assessment of Cancer Therapy scale were also administered. On average, total sleep time was 5.9 (SD = 1.4) h, and sleep efficiency was 75% (SD = 12.0) as assessed by actigraphy. There was generally poor concordance between actigraphy and daily diary for most sleep metrics. Subjects reported awakening, on average, 2.7 times per night, most commonly for nocturia and hot flashes. Assessment of daily functioning showed that participants had mild daytime sleepiness, which was predicted by total sleep time (F(1,47) = 4.5, P= 0.04) General quality of life was not impaired. This study supports more research on the predictors of poor sleep in order to identify effective interventions.

Sleep in the elderly.

Older adults frequently experience difficulties with sleep that can be caused by specific sleep disorders (such as sleep-disordered breathing or periodic limb movements in sleep) and circadian rhythm disturbances. These all can be effectively treated. Medical illnesses and medications also can have a negative affect on sleep and effective management of these can significantly improve sleep in older adults. Sleep in institutionalized older adults is even more disturbed than sleep of community-dwelling older people and special considerations can be made to improve the quality of sleep in institutional settings.

Rapid eye movement sleep changes during the adaptation night in combat veterans with posttraumatic stress disorder.

BACKGROUND: Hyperarousal in posttraumatic stress disorder (PTSD) is manifested during sleep as well as waking. Elevated rapid eye movement sleep (REMS) phasic activity, likely signifying central nervous system alerting, has been identified in PTSD. The authors reasoned that PTSD compared to control subjects would show particularly increased REMS phasic activity on the first night of polysomnography, with adaptation to a novel environment. METHODS: First-night polysomnograms of 17 veterans with PTSD were compared with those of 11 control subjects. Sleep was also studied in subsets of both groups over two nights. RESULTS: On the first night, the PTSD subjects had a higher density of rapid eye movements in the first REMS period. This measure was increased on the first compared to the second night, but there was no interaction effect between night and group. CONCLUSIONS: REMS changes are again demonstrated in veterans with PTSD. Introduction to a novel environment activated a REMS phasic process, but not differentially in PTSD compared to control subjects.