Primary insomnia: A disorder of sleep, or primarily one of wakefulness?

Enhanced Vigilance Stability during Daytime in Insomnia Disorder

Central nervous hyperarousal is as a key component of current pathophysiological concepts of chronic insomnia disorder. However, there are still open questions regarding its exact nature and the mechanisms linking hyperarousal to sleep disturbance. Here, we aimed at studying waking state hyperarousal in insomnia by the perspective of resting-state vigilance dynamics. The VIGALL (Vigilance Algorithm Leipzig) algorithm has been developed to investigate resting-state vigilance dynamics, and it revealed, for example, enhanced vigilance stability in depressive patients. We hypothesized that patients with insomnia also show a more stable vigilance regulation. Thirty-four unmedicated patients with chronic insomnia and 25 healthy controls participated in a twenty-minute resting-state electroencephalography (EEG) measurement following a night of polysomnography. Insomnia patients showed enhanced EEG vigilance stability as compared to controls. The pattern of vigilance hyperstability differed from that reported previously in depressive patients. Vigilance hyperstability was also present in insomnia patients showing only mildly reduced sleep efficiency. In this subgroup, vigilance hyperstability correlated with measures of disturbed sleep continuity and arousal. Our data indicate that insomnia disorder is characterized by hyperarousal at night as well as during daytime.

Sleep and cognitive performance: cross-sectional associations in the UK Biobank

OBJECTIVE

The relationship between insomnia symptoms and cognitive performance is unclear, particularly at the population level. We conducted the largest examination of this association to date through analysis of the UK Biobank, a large population-based sample of adults aged 40-69 years. We also sought to determine associations between cognitive performance and self-reported chronotype, sleep medication use and sleep duration.

METHODS

This cross-sectional, population-based study involved 477,529 participants, comprising 133,314 patients with frequent insomnia symptoms (age: 57.4 ± 7.7 years; 62.1% female) and 344,215 controls without insomnia symptoms (age: 56.1 ± 8.2 years; 52.0% female). Cognitive performance was assessed by a touchscreen test battery probing reasoning, basic reaction time, numeric memory, visual memory, and prospective memory. Adjusted models included relevant demographic, clinical, and sleep variables.

RESULTS

Frequent insomnia symptoms were associated with cognitive impairment in unadjusted models; however, these effects were reversed after full adjustment, leaving those with frequent insomnia symptoms showing statistically better cognitive performance over those without. Relative to intermediate chronotype, evening chronotype was associated with superior task performance, while morning chronotype was associated with the poorest performance. Sleep medication use and both long (>9 h) and short (<7 h) sleep durations were associated with impaired performance.

CONCLUSIONS

Our results suggest that after adjustment for potential confounding variables, frequent insomnia symptoms may be associated with a small statistical advantage, which is unlikely to be clinically meaningful, on simple neurocognitive tasks. Further work is required to examine the mechanistic underpinnings of an apparent evening chronotype advantage in cognitive performance and the impairment associated with morning chronotype, sleep medication use, and sleep duration extremes.

Peeking into the minds of troubled adolescents: the utility of polysomnography sleep studies in an inpatient psychiatric unit

BACKGROUND

Sleep problems are commonly associated with the primary diagnostic criteria for many psychiatric disorders. Evidence suggests sleep disturbances may precede development of psychiatric disorders and the severity of psychopathology reflects the severity of sleep problems. Polysomnography (PSG) sleep studies in child and adolescent psychiatric populations, a particularly at risk group, has considerable value but has been more elusive requiring further investigation.

METHODS

We performed a retrospective chart review of PSG sleep studies and psychiatrist evaluations of 106 adolescents aged 7-16 admitted to an involuntary adolescent psychiatric inpatient facility.

RESULTS

Less than 5% of cases had mild/no sleep problems. Hyperarousal hallmarked this population, and severity of sleep disturbances trends with the severity of psychopathology. Inpatients with multiple psychiatric disorders had greater frequencies of insomnia, decreased sleep efficiency, and arousals from SWS (p<0.05). Inpatient's with self-harm behavior more frequently had elevated sleep onset latency (SOL), reduced efficiency, reduced SWS (p<0.05), increased REM, and reduced REM latency compared to inpatients with dysthymia and/or depression.

LIMITATIONS

Lacking an a priori hypothesis, this study was explorative and uncontrolled for factors such as medications. This notwithstanding however, analysis indicates the majority of inpatients were taking cocktails that "should" alleviate sleep symptoms suggesting greater associations may prevail in unmedicated populations.

CONCLUSIONS

This study attests to the potential clinical utility of PSG sleep studies in the management of adolescent psychiatric disorders and contributes to the body of evidence reputing the intimate connection between sleep problems and the development and perpetuation of psychopathology with public health implications.

No pain, no gain: an exploratory within-subjects mixed-methods evaluation of the patient experience of sleep restriction therapy (SRT) for insomnia

OBJECTIVE

To explore the patient experience of Sleep Restriction Therapy (SRT) for insomnia, with particular focus on elucidating possible side-effects, challenges to adherence and implementation and perceptions of benefit/impact.

METHODS

To fully investigate the patient experience of sleep restriction therapy for insomnia we designed a within-subjects mixed-method study, employing sleep and daytime functioning questionnaires, assessments of sleep-restriction-related side-effects, prospective qualitative audio-diaries and post-treatment semi-structured interviews. University of Glasgow Sleep Centre. Eighteen patients with Primary Insomnia (mean age=42; range 18-64). Patients took part in a 4-week brief sleep restriction intervention, involving two group sessions and two subsequent follow-up phone calls in the home environment.

MEASUREMENTS AND RESULTS

Sleep diaries and global measures of insomnia severity and sleep quality, as expected, demonstrated robust improvements at both post-treatment and 3-month follow-up (all large effect sizes). Daytime functioning/health-related quality of life variables similarly evidenced strong treatment effects (moderate to large effect sizes). Reported side-effects were common, with ≥50% of patients reporting impairment in 8 out of 12 listed symptoms as a consequence of initiating treatment. The four most common side-effects were 'fatigue/exhaustion' (100%), 'extreme sleepiness' (94%), 'reduced motivation/energy' (89%) and 'headache/migraine' (72%) [Mean number of symptoms per patient=7.2 (2.4); range 3-11]. Intriguingly, both side-effect frequency and ratings of side-effect interference were associated with baseline to post-treatment improvements in sleep quality. Qualitative real-time audio-diaries during week 1 of treatment and post-treatment interviews provided rich accounts of side-effects associated with acute SRT implementation; general challenges surrounding treatment implementation and adherence/non-adherence; and modifications to sleep parameters, daytime functioning and perceptions of sleep/sleep period.

CONCLUSIONS

This work has important implications for the delivery of SRT, particularly concerning awareness of possible 'adverse events' and likely implementation/adherence challenges. Findings also pave the way for testable hypotheses concerning possible mechanisms of action involved in sleep restriction treatment.

Obesity and short sleep: unlikely bedfellows?

The link between habitual short sleep and obesity is critically examined from a sleep perspective. Sleep estimates are confounded by 'time in bed', naps; the normal distribution of sleep duration. Wide categorizations of 'short sleep', with claims that <7 h sleep is associated with obesity and morbidity, stem from generalizations from 5 h sleepers (<8% of adults) and acute restriction studies involving unendurable sleepiness. Statistically significant epidemiological findings are of questionable clinical concern, even for 5 h sleepers, as any weight gains accumulate slowly over years; easily redressed by e.g. short exercise exposures, contrasting with huge accumulations of 'lost' sleep. Little evidence supports 'more sleep', alone, as an effective treatment for obesity. Impaired sleep quality and quantity are surrogates for many physical and psychological disorders, as can be obesity. Advocating more sleep, in these respects, could invoke unwarranted use of sleep aids including hypnotics. Inadequate sleep in obese children is usually symptomatic of problems not overcome by increasing sleep alone. Interestingly, neuropeptides regulating interactions between sleep, locomotion and energy balance in normal weight individuals, are an avenue for investigation in some obese short sleepers. The real danger of inadequate sleep lies with excessive daytime sleepiness, not obesity.

The end of sleep: 'sleep debt' versus biological adaptation of human sleep to waking needs

It is argued that the latter part of usual human sleep is phenotypically adaptable (without 'sleep debt') to habitual shortening or lengthening, according to environmental influences of light, safety, food availability and socio-economic factors, but without increasing daytime sleepiness. Pluripotent brain mechanisms linking sleep, hunger, foraging, locomotion and alertness, facilitate this time management, with REM acting as a 'buffer' between wakefulness and nonREM ('true') sleep. The adaptive sleep range is approximately 6-9h, although, a timely short (<20 min) nap can equate to 1h 'extra' nighttime sleep. Appraisal of recent epidemiological findings linking habitual sleep duration to mortality and morbidity points to nominal causal effects of sleep within this range. Statistical significance, here, may not equate to real clinical significance. Sleep durations outside 6-9h are usually surrogates of common underlying causes, with sleep associations taking years to develop. Manipulation of sleep, alone, is unlikely to overcome these health effects, and there are effective, rapid, non-sleep, behavioural countermeasures. Sleep can be taken for pleasure, with minimal sleepiness; such 'sleepability' is 'unmasked' by sleep-conducive situations. Sleep is not the only anodyne to sleepiness, but so is wakefulness, inasmuch that some sleepiness disappears when wakefulness becomes more challenging and eventful. A more ecological approach to sleep and sleepiness is advocated.