A NORMATIVE STUDY OF THE MAINTENANCE OF WAKEFULNESS TEST (MWT)

The maintenance of wakefulness test (MWT) is a daytime polysomnographi c procedure which quantifies wake tendency by measuring the ability to remain awake during soporific circumstances. We present normative dat a based on 64 healthy subjects (27 males and 37 females) who adhered t o uniform MWT procedural conditions including polysomnographic montage , illuminance level, seating position, room temperature, meal timing, and subject instructions. When allowed a maximum trial duration of 40 min, subjects' mean sleep latency to the first epoch of sustained slee p was 35.2 +/- 7.9 min. The lower normal limit, defined as two standar d deviations below the mean, was 19.4 min. Calculation of data on the basis of a maximum trial duration of 20 min and sleep latency to the f irst appearance of brief sleep (a microsleep episode or one epoch of a ny stage of sleep) yielded a mean sleep latency of 18.1 +/- 3.6 min an d a lower normal limit of 10.9 min. Sleep latency scores were signific antly higher than those previously reported in patients with disorders of excessive somnolence. Therefore, the MWT appears to be a useful pr ocedure in differentiating groups with normal daytime wake tendency fr om those with impaired wake tendency and in identifying individuals wi th pathologic inability to remain awake under soporific circumstances. (C) 1997 Elsevier Science Ireland Ltd.