Anna Kis1, Péter Simor1, Klára Horváth2, Róbert Bódizs2

1Budapest University of Technology and Economics, Department of Cognitive Sciences

2Semmelweis Medical University, Institute of Behavioural Sciences “>

The first night effect – marked differences between the first and the second night spent in a sleep laboratory – is a widely known fact that accounts for the common practice of excluding the first night sleep from any polysomnographic analysis. The extent to which the first night effect is present in a subject and the duration of this effect (one or more nights) might have diagnostic value as well and should account for different protocols used for distinct patient groups. In the present study we conducted a two nights long polysomnographic recording on 16 (nightmare sufferer and control) subjects supplemented by data obtained from the Groningen Sleep Quality Scale for both nights. Differences were found in both the objective (sleep duration, sleep efficiency, wakings after sleep onset, relative S1 duration, relative S2 duration and relative slow wave sleep duration) and subjective (self-rating) variables between the two nights. Results suggest that contrary to previous findings data obtained from a self-rating questionnaire can be a useful measurement of the first night effect. Therefore we suggest the clinical use of the Groningen Sleep Quality Scale before and during polysomnographic recordings in order to have a “home baseline” sleep value.

Key words: sleep, first night effect, polysomnography, Groningen Sleep Quality Scale