Extended Work Schedules, Sleep Loss and Health

Inclusion Criteria: * normal healthy men and women between the ages of 21 years and 39 years (inclusive) with normal weight (i.e., body mass index under 28 kg/m2 in men, 27 kg/m2 in women) * normal findings on clinical examination, normal results on routine laboratory tests, normal EKG, normal glucose tolerance test, negative pregnancy test for women * no personal history of psychiatric or endocrine illness * no personal history of sleep disorder, usual total sleep time of at least 7 hours * only female volunteers with normal ovulatory cycles will be included Exclusion Criteria: * subjects with irregular life habits (shiftworkers and subjects having traveled across time zones less than one month prior to the beginning of the baseline study) * subjects taking any medication (including hormonal contraceptive therapy), and smokers are excluded * subjects with significant sleep apnea (apnea index above 10) or significant arousal-associated periodic leg movements are excluded