Assessing sleep-wake survival dynamics in relation to sleep quality in a placebo-controlled pharmacological intervention study with people with insomnia and healthy controls.
RATIONALE
The mechanisms underlying impaired sleep quality in insomnia are not fully known, but an important role for sleep fragmentation has been proposed.


OBJECTIVES
The aim of this study is to explore potential mechanisms of sleep fragmentation influencing alterations of perceived sleep quality.


METHODS
We analyzed polysomnography (PSG) recordings from a double-blind crossover study with zopiclone 7.5 mg and placebo, in elderly participants with insomnia complaints and age-matched healthy controls. We compared survival dynamics of sleep and wake across group and treatment. Subsequently, we used a previously proposed model to estimate the amount of sleep onset latency (SOL) misperception from PSG-defined sleep fragmentation. Self-reported and model-estimated amount of SOL misperception were compared across group and treatment, as well as model prediction errors.


RESULTS
In the zopiclone night, the average segment length of NREM sleep was increased (group F = 1.16, p = 0.32; treatment F = 8.89, p < 0.01; group x treatment F = 0.44, p = 0.65), while the segment length of wake was decreased (group F = 1.48, p = 0.23; treatment F = 11.49, p < 0.01; group x treatment F = 0.36, p = 0.70). The self-reported and model-estimated amount of SOL misperception were lower during the zopiclone night (self-reported group F = 6.08, p < 0.01, treatment F = 10.8, p < 0.01, group x treatment F = 2.49, p = 0.09; model-estimated F = 1.70, p = 0.19, treatment F = 16.1, p < 0.001, group x treatment F = 0.60, p = 0.55). The prediction error was not altered (group F = 1.62, p = 0.20; treatment F = 0.20, p = 0.65; group x treatment F = 1.01, p = 0.37).


CONCLUSIONS
Impaired subjective sleep quality is associated with decreased NREM stability, together with increased stability of wake. Furthermore, we conclude that zopiclone-induced changes in SOL misperception can be largely attributed to predictable changes of sleep architecture.
['Hermans|Lieke W A|LWA|http://orcid.org/0000-0002-2069-4105', 'Regis|Marta|M|', 'Fonseca|Pedro|P|', 'Overeem|Sebastiaan|S|', 'Leufkens|Tim R M|TRM|', 'Vermeeren|Annemiek|A|', 'van Gilst|Merel M|MM|']
D000328:Adult D000368:Aged D053961:Azabicyclo Compounds D002986:Clinical Trials as Topic D018592:Cross-Over Studies D004311:Double-Blind Method D005260:Female D006801:Humans D008297:Male D008875:Middle Aged D010879:Piperazines D017286:Polysomnography D057566:Self Report D012892:Sleep Deprivation D007319:Sleep Initiation and Maintenance Disorders D012895:Sleep, REM
Insomnia Sleep fragmentation Zopiclone Sleep onset latency Sleep state misperception