We systematically examined the temporal relationships between subjective sleepiness and both physiological drowsiness and performance impairment in a controlled laboratory setting. Eighteen healthy young adults (8 women; M_AGE = 21.44 ± 3.24 years) underwent 40 hr of extended wakefulness, completing a bihourly Karolinska Sleepiness Scale (KSS) and 10-min Psychomotor Vigilance Task (PVT). Microsleeps and slow eye movements (SEMs) were scored during the PVT. KSS scores increased 3 hr prior to performance impairment (p < .001) and 4–6 hr prior to physiological sleepiness (p < .001). There were strong within-subject correlations between KSS and PVT lapses (r = 0.75, p < .001) and physiological drowsiness (r > 0.60, p < .001). Between-subjects product-moment correlations were more modest but showed a significant positive increase across time awake, suggesting that subjective sleepiness and objective outcomes were more tightly correlated after sleep loss. Cross-correlations showed significant positive correlations at 0-lag (p < .034); however, a high proportion of participants showed maximal correlations at positive lags, suggesting KSS was associated with future objective impairment. Within individuals, subjective sleepiness was highly correlated with objective impairment, between-subject correlations were more modest, possibly due to interindividual vulnerability to sleep loss. These results suggest that subjective sleepiness represents an inbuilt early warning system for subsequent drowsiness and performance impairment.

中文翻译：

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嗜睡意识：主观和客观嗜睡的时间动态

我们在受控的实验室环境中系统地检查了主观嗜睡与生理嗜睡和表现障碍之间的时间关系。18 名健康青年（8 名女性；M _AGE  = 21.44 ± 3.24 岁）经历了 40 小时的延长清醒期，完成了每两小时的卡罗林斯卡嗜睡量表 (KSS) 和 10 分钟的精神运动警觉任务 (PVT)。在 PVT 期间对微睡眠和慢眼动 (SEM) 进行评分。KSS 分数在表现障碍前 3 小时（p  < .001）和生理嗜睡前 4-6 小时（p  < .001）增加。KSS 和 PVT 失误之间存在很强的受试者内相关性（r  = 0.75，p < .001) 和生理嗜睡 ( r  > 0.60, p  < .001)。受试者之间的乘积-时刻相关性更为温和，但随着清醒时间的推移显示出显着的正增长，这表明主观嗜睡和客观结果在睡眠不足后更加紧密相关。互相关在 0 滞后时显示出显着的正相关 ( p < .034); 然而，高比例的参与者在正滞后时表现出最大的相关性，这表明 KSS 与未来的客观损害有关。在个体内部，主观嗜睡与客观损害高度相关，受试者之间的相关性更为温和，可能是由于个体间易受睡眠损失的影响。这些结果表明，主观嗜睡代表了随后的嗜睡和表现障碍的内置预警系统。