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Session: Sleep
Session starts: Thursday 24 January, 10:30
Presentation starts: 11:15
Room: Lecture room 558

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Lieke Hermans ()
Tim Leufkens ()
Merel van Gilst ()
Tim Weysen ()
Marco Ross ()
Peter Anderer ()
Sebastiaan Overeem ()
Annemiek Vermeeren ()

Abstract:
Insomnia patients often overestimate their sleep onset latency (SOL). The mechanism underlying this type of sleep state misperception is not fully understood. We hypothesize that the length of uninterrupted sleep fragments after sleep onset influences the perception of the SOL because too short sleep fragments might be overlooked. We attempt to make a model of the minimum length that a sleep fragment should have in order to be perceived as sleep, and we fit the model to subjective data of insomniacs and healthy controls. Standard in-lab polysomnographic recordings were performed in 20 elderly, untreated insomniacs and 21 age-matched self-defined good sleepers. Recordings were visually scored according to R&K criteria1. In the model sleep onset was defined as the first epoch of the first sleep fragment longer than L minutes, with L varying from 0.5 to 40. We selected the length L that resulted in the smallest Mean Square Error (MSE) of the difference between modelled SOL and SOL perceived by the subject. This was done for both subject groups separately. For insomniacs, the lowest MSE was found for a length L of 30 minutes (MSE without model: 7195 vs. L=30: 3927). In the healthy subjects, applying the model only resulted in small improvements of the MSE. The lowest MSE was found for L=10 (MSE without model: 1185 vs. L=10: 969), although the results for all model parameters L below 20 were very similar. The aim of this study was to investigate the mechanisms underlying sleep onset misperception, by modelling the influence of sleep interruption on subjective SOL. The results indicate that in insomnia patients the perception of sleep onset can be influenced if a sleep fragment is interrupted after less than 30 minutes. The different results for the two groups suggest that, for the perception of sleep onset, insomniacs are more sensitive to sleep interruption than healthy subjects. In order to extend our findings to the general population, the analysis should be repeated in different age groups. Additionally, other parameters could be added to the model, for instance sleep depth and the duration of the sleep disruption.