What does the multiple sleep latency test measure in a community sample?

Multiple sleep latency test (MSLT)-defined daytime sleepiness and its relationships with nocturnal and daytime psychophysiological activation were investigated in a random community sample of 77 subjects aged 35-55 years. The correlation structure between all study variables was explained by a simple model of daytime sleepiness. The model suggested that indicators of psychophysiological arousal (psychological distress, nocturnal motor activity and serum thyrotropin level) and daytime reported tiredness, body mass index (BMI) and age were related significantly and independently to MSLT-defined daytime sleepiness. The arousal theory of insomnia and poor sleep in relation to MSLT behavior is discussed and the need of a multivariate approach is emphasized in MSLT studies.