Subjective sleepiness ratings: the effects of sleep deprivation, circadian rhythmicity and cognitive performance.
ABSTRACT Computerized self-report sleepiness scales were administered before and after cognitive testing in a 72-hour sleep deprivation study. The cognitive test battery was administered every 2 hours and took approximately 1-1.25 hours. Two computerized measures of subjective sleepiness were used, one a visual analog scale, the other a Hebrew version of the Stanford sleepiness scale. The results indicated that both accumulated sleep loss, circadian and ultradian (2 cycles/day) factors were significant in determining subjective estimates of sleepiness. The extent of the differences between subjective sleepiness ratings before cognitive testing and after testing was dependent upon the phase of the circadian cycle. These differences were greatest at approximately 0200-0600 hours and least around 1000 hours. A second low point occurred at 1800-2000 hours. Analysis by complex demodulation of the individual subjects' sleepiness rating curves indicated that the amount of variance accounted for by the circadian component increased significantly after cognitive testing.
- [Show abstract] [Hide abstract]
ABSTRACT: To identify baseline behavioral and physiologic markers that associate with individual differences in sustained attention during sleep deprivation. In a retrospective study, ocular, electrocardiogram, and electroencephalogram (EEG) measures were compared in subjects who were characterized as resilient (n = 15) or vulnerable (n = 15) to the effects of total sleep deprivation on sustained attention. Chronobiology and Sleep Laboratory, Duke-NUS Graduate Medical School Singapore. Healthy volunteers aged 22-32 years from the general population. Subjects were kept awake for at least 26 hours under constant environmental conditions. Every 2 hours, sustained attention was assessed using a 10-minute psychomotor vigilance task (PVT). During baseline sleep and recovery sleep, EEG slow wave activity was similar in resilient versus vulnerable subjects, suggesting that individual differences in vulnerability to sleep loss were not related to differences in homeostatic sleep regulation. Rather, irrespective of time elapsed since wake, subjects who were vulnerable to sleep deprivation exhibited slower and more variable PVT response times, lower and more variable heart rate, and higher and more variable EEG spectral power in the theta frequency band (6.0-7.5 Hz). Performance decrements in sustained attention during sleep deprivation associate with instability in behavioral and physiologic measures at baseline. Small individual differences in sustained attention that are present at baseline are amplified during prolonged wakefulness, thus contributing to large between-subjects differences in performance and sleepiness. Chua EC; Yeo SC; Lee IT; Tan LC; Lau P; Cai S; Zhang X; Puvanendran K; Gooley JJ. Sustained attention performance during sleep deprivation associates with instability in behavior and physiologic measures at baseline. SLEEP 2014;37(1):27-39.Sleep 01/2014; 37(1):27-39. · 5.06 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Abstract This investigation examined precompetitive sleep behaviour of 103 athletes and how it relates to precompetitive mood and subsequent performance. Results revealed that on the night before competition athletes slept well under the recommended target of eight hours of sleep for healthy adults, with almost 70% of athletes experiencing poorer sleep than usual. It was found that anxiety, noise, the need to use the bathroom and early event times were amongst the most commonly reported causes of disrupted sleep in athletes on the night prior to competition. The negative moods of fatigue and tension were both significantly negatively correlated with precompetitive relative sleep quality (r = -0.28, P = 0.004, r = -0.21, P = 0.030, respectively) and total sleep time (r = -0.23, P = 0.023, r = -0.20, P = 0.044, respectively). Additionally, tension was positively correlated with number of awakenings (r = -0.20, P = 0.045). Vigour was seen to be significantly positively associated with relative sleep quality (r = 0.24, P=0.013). The relationships between relative sleep quality and fatigue, tension and vigour accounted for approximately 4 - 5% of the variance in mood scores. Disrupted sleep did not demonstrate any significant relationship with relative sporting performance. Conclusions from the present investigation are that athletes may be at particular risk of disrupted sleep on the night prior to competition, and this disruption can negatively relate to an athlete's precompetitive mood states.European journal of sport science. 01/2014; 14(sup1):S123-S130.