Conditional Probability of Observing a Poor Night According to Sleep Depth Among Individuals With Insomnia

The present study aims at verifying whether the conditional probability of observing a poor night after one, two, or three consecutive poor nights is associated with sleep depth or sleep self-estimation. Online sleep diaries were collected for 21 consecutive nights from 30 adults with insomnia. Participants completed seven consecutive nights of home polysomnography starting on night 1, 8, or 15 of the sleep diary. The conditional probabilities of observing a poor night after one, two, or three consecutive poor nights were computed for each participant. Sleep depth was measured with the Odds Ratio Product. K-Means Cluster Analyses were computed to derive sleep patterns. Pearson's correlation tests and ANOVAs were conducted to verify the existence of relations with conditional probabilities of observing poor nights and characterise identified sleep patterns. The conditional probability of observing a poor night after one, two, or three consecutive poor nights increased with objective and self-reported WASO, self-reported TWT, and sleepiness before bedtime. The probability increased on sleep depth; thus, the lack of sleep depth was more pronounced. Conversely, the probability increased as subjective SE decreased. Two sleep patterns in insomnia were derived from sleep diaries. Individuals for whom the conditional probability of having consecutive poor nights is high and constant tend to exhibit a reduced sleep depth. Cortical and physiological arousal might play a key role in the development and maintenance of sleep patterns in insomnia. Sleep self-estimation does not appear to be influenced by the conditional probability of experiencing a poor night after consecutive poor nights.