Clinical Research Directory

Inclusion Criteria: * excessive daytime sleepiness (Epworth Sleepiness Scale score \> 9), * sleep complaint such as sleep apnea or insomnia (Basic Nordic Sleep Questionnaire, items score \< 4 except questions 3, 4 and 15a for aged volunteers), * not intermediate in terms of morningness and eveningness according to the Horne-Ostberg questionnaire for young volunteers * absence of psychopathology evidenced during psychologist interview or on the Symptom Check List (SCL-90R score\>59) * sleep efficiency evidenced by actimetry (\>85%) during 7 days * absence of apnea/hypopnea syndrome (RDI\<15) * absence of periodic movement disorder (MPS\<15) * regular sleep schedule during 3 days before study participation * affiliated to the french health care system Exclusion Criteria: * volunteers with sleep disorders or organic disorders affecting sleep, * poor sleep hygiene or abnormal usual sleep patterns, * night workers or shift-workers, * substance abusers (caffeine, drug, or alcohol).