EXTENDED WORK SCHEDULES AND HEALTH: ROLE OF SLEEP LOSS

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Millions of individuals have extended work schedules and/or work schedules that result in circadian misalignment. Epidemiological studies and surveys indicate that such schedules nearly always result in restriction on the time allocated to sleep and that they are associated with adverse health outcomes. The mechanisms underlying the adverse health effects of these schedules are poorly understood and probably involve multiple psychosocial and pathophysiological pathways. This protocol addresses possible roles of sleep loss and circadian disruption in mediating some of the adverse health impact of shifted work schedules. The study is designed to test the hypotheses that 1. sleep loss as occurs during extended work schedules may result in adverse health consequences and that 2. circadian maladaptation, independently of sleep loss, has intrinsic adverse health consequences. Two groups of gender and age-matched healthy subjects age 21-39 will undergo either 1. simulation of extended activity without circadian disruption (night-time sleep of 5h) or 2. simulation of extended activities with rotations between daytime and nighttime activity (5h of daytime or nighttime sleep). The total number of bedtime hours is identical in both protocols. Metabolic, endocrine, cardiovascular and neurobehavioral functions are examined under baseline condition and at the end of 8 days of restricted bedtimes. An intermediate assessment using non-invasive procedures is conducted at the mid point of the period of sleep restriction. Assessments of stress-responsive systems (urinary catecholamines and saliva cortisol), carbohydrate metabolism and neurobehavioral function are also conducted after partial sleep recovery.