The Natural History of Insomnia: Sleep Opportunity Extension Following a Poor Night of Sleep Is Not Related to the Transition From Acute to Chronic Insomnia.

The behavioural tendency to expand sleep opportunity to compensate for prior sleep loss is referred to as 'sleep extension.' It is believed that sleep extension (here referred to as 'sleep opportunity extension' [SOE]) is the primary perpetuating factor explaining the transition from acute to chronic insomnia. Recently, this proposition was prospectively evaluated by assessing how sleep opportunity varied, week-by-week, relative to the incidence of acute and chronic insomnia. Significant differences in sleep opportunity before and after onset of acute insomnia were not detected. In the present analysis, a more granular evaluation was undertaken to assess whether SOE occurs on the nights and/or weekends following poor sleep. The data set (n = 1243) was modelled by group (good sleepers and participants with acute insomnia) for SOE occurring on the nights and weekends following poor nights of sleep (i.e., ≥ 30 min of sleep latency and/or nocturnal wakefulness and/or early morning awakenings) for the post-acute insomnia interval. A linear mixed effects model was used to account for up to one year of night-to-night sleep per participant. During the weekdays, sleep opportunity following a poor night of sleep was not found to increase (overall or by group) (< 5 min). During the weekends, all groups tended to decrease their sleep opportunity. This counterintuitive finding casts further doubt on the proposition that SOE is responsible for the transition between acute insomnia and chronic insomnia. This finding does not, however, change the relevance of addressing the mismatch between sleep opportunity and ability as part of behavioural treatment.