Roles of sleep in cognitive, neural and physiological functions

The goal of the proposed research program is to contribute to our understanding of the roles played by sleep in human physiology and behaviour. We are interested in several aspects of how sleep contributes to normal physiological functions and how sleep loss affects important regulatory mechanisms.One goal is to better understand how sleep influences appetite and body weight by regulating hormones that are involved in metabolism. A particular focus is on how sleep interacts with changing endocrine profiles in women to alter appetite and body weight regulation. We will investigate the impact of either acute or more chronic sleep loss on endocrine activity and on regulation of food intake in young women in different hormonal states at different phases of their menstrual cycles. We will also investigate how these impacts of sleep loss are potentially altered in women who have undergone the hormonal changes related to menopause. There is no information available about how sleep disruption, which is common during this period, affects metabolism at this stage of life.We will also study how sleep affects cognitive functions and the neural mechanisms that may mediate the role of sleep in helping to consolidate newly acquired skills, using two methods of recording brain activity: electroencephalography and magnetoencephalography. We will study the role of daytime naps in reversing the effects of sleep loss on this consolidation process. The main tool to be used to assess the role of sleep is manipulating sleep durations, either acutely or chronically, to assess the effects on physiology and behaviour. The basic knowledge we propose to acquire about the functions of sleep may ultimately be applicable to improving work/rest scheduling in transportation, manufacturing, protection services and other economic sectors.