No abstract

The maintenance of wakefulness test (MWT) is a daytime polysomnographic procedure which quantifies wake tendency by measuring the ability to remain awake during soporific circumstances. We present normative data based on 64 healthy subjects (27 males and 37 females) who adhered to 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 sleep was 35.2 +/- 7.9 min. The lower normal limit, defined as two standard 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 first appearance of brief sleep (a microsleep episode or one epoch of any stage of sleep) yielded a mean sleep latency of 18.1 +/- 3.6 min and a lower normal limit of 10.9 min. Sleep latency scores were significantly higher than those previously reported in patients with disorders of excessive somnolence. Therefore, the MWT appears to be a useful procedure in differentiating groups with normal daytime wake tendency from those with impaired wake tendency and in identifying individuals with pathologic inability to remain awake under soporific circumstances.

Body temperature has a circadian rhythm, and in women with ovulatory cycles, also a menstrual rhythm. Body temperature and sleep are believed to be closely coupled, but the influence on their relationship of gender, menstrual cycle phase and female reproductive hormones is unresolved. We investigated sleep and 24 h rectal temperatures in eight women with normal menstrual cycles in their mid‐follicular and mid‐luteal phases, and in eight young women taking a steady dose of oral progestin and ethinyl oestradiol (hormonal contraceptive), and compared their sleep and body temperatures with that of eight young men, sleeping in identical conditions. All subjects maintained their habitual daytime schedules. Rectal temperatures were elevated throughout 24 h in the luteal phase compared with the follicular phase in the naturally cycling women, consistent with a raised thermoregulatory set‐point. Rectal temperatures in the women taking hormonal contraceptives were similar to those of the naturally cycling women in the luteal phase. Gender influenced body temperature: the naturally cycling women and the women taking hormonal contraceptives attained their nocturnal minimum body temperatures earlier than the men, and the naturally cycling women had blunted nocturnal body temperature drops compared with the men. Sleep architecture was essentially unaffected by either menstrual cycle phase or gender. The women taking hormonal contraceptives had less slow wave sleep (SWS), however, than the naturally cycling women. Gender, menstrual cycle phase and hormonal contraceptives significantly influenced body temperature, but had only minor consequences for sleep, in the young men and women in our study.

Excessive training is reported to cause sleep disturbances and mood changes. We examined sleep and psychological changes in female swimmers across a competitive swimming season, that is, at the start of the season (onset), during peak training period (peak), and after a precompetition reduction in training (taper). For each phase, polysomnographic recordings, body composition, psychological parameters, and swimming performance were obtained. A daily training log and sleep diary were maintained for the entire study period. Sleep onset latency (SOL) time awake after sleep onset, total sleep time (TST), and rapid eye movement (REM) sleep times were similar at all three training levels. Slow wave sleep (SWS) formed a very high percentage of total sleep in the onset (26%) and peak (31%) training periods, but was significantly reduced following precompetition taper (16%), supporting the theory that the need for restorative SWS is reduced with reduced physical demand. The number of movements during sleep was significantly higher at the higher training volumes, suggesting some sleep disruption. In contrast to other studies, mood deteriorated with a reduction in training volume and/or impending competition.

Our study investigated endurance performances in a performance-matched (running 42.2 km) group of females (N = 10) and males (N = 10). The distances examined were 10 km, 21.1 km, 42.2 km, and 90 km. Measurements included VO2max, running economy, lactate accumulation, and running speeds. Although our female subjects performed as well as their male counterparts at 42.2 km (194.8 +/- 12.9 m.min-1 vs 192.6 +/- 16.3 m.min-1), the performance for 90 km was significantly better (P < 0.05) in the female group (171.0 +/- 11.7 m.min-1 vs 155.2 +/- 14.7 m.min-1). The average fraction of the VO2max (F) sustained by each subject indicated that the females achieved their performances by working at a higher (P < 0.01) F (73.4 +/- 5.5% vs 66.3 +/- 3.7% for 42.2 km and 59.8 +/- 6.2% vs 50.2 +/- 3.1% for 90 km). The degree of decline in the fraction of the VO2max sustained as the distance of running increased was significantly less (P < 0.05) in the females. The better performance by the females at 90 km was not related to greater maximal aerobic capacity, running economy, training level, or fatty acid metabolism.