[Individual differences and sleep deprivation effects].

Contemporary lifestyle and different life circumstances often require that individuals restrict their sleep duration and change their sleep schedule. That often leads to sleep deprivation. Former studies showed that sleep deprivation effects on the physiological and psychological functioning of an individual depended on numerous factors such as type of sleep deprivation, previous sleep duration, time of day when the effects were examined, characteristics of tasks performed, and the subject's motivation. This paper discusses the effects of sleep deprivation and the existence of stable individual differences in those effects, named "vulnerability to sleep loss". Recent studies indicate that some characteristics of the subjects could help predict systematic and robust sleep deprivation effects, such as age, sex and personality characteristics. Furthermore, the article discusses the importance of individual differences in specific characteristics related to sleep and wakefulness like those in preferred circadian phase, sleep need, individual level of sleepiness, and the ability to fall asleep quickly. So far, studies of individual characteristics did not result in consistent conclusions about their predictive importance for vulnerability to sleep loss. Further studies directed at this problem could help identify individuals who are more vulnerable to sleep loss, and contribute to personal and public safety of night work.