Neurobehavioural impacts of chronic sleep restriction

Insomnia and disrupted sleep are increasingly recognized as having important effects on human health and safety, and as having a major economic impact. How much chronic sleep loss affects health and behaviour may depend on how effectively lost sleep can be compensated for by recovery sleep. Yet we know little about how sleep patterns change under chronic sleep loss and how they recover during later sleep opportunities. Animal models allow researchers to study how the body and brain respond to chronic sleep loss and attempt to recover sleep. We recently developed a new rat model of chronic sleep loss that takes into account rats' natural polyphasic sleep tendencies. We now propose to use this model to examine the effects of chronic sleep loss and recovery sleep on behaviour and physiology. Rats will be sleep deprived during repeated cycles over four days and allowed to show recovery sleep between deprivation cycles and after the four days. Sleep patterns and other physiological measures, such as heart rate and body temperature, will be recorded before, during, and after sleep loss. We will study how the biological clock influences the adaptation to, and recovery from, chronic sleep loss, and how chronic sleep loss affects the brain and the body's ability to maintain a biologically adaptive and stable internal environment. We will also examine how sleep restriction affects the rat's ability to maintain attention during task performance, which is the cognitive problem resulting from sleep loss that is most problematic for people. We will also try to identify brain changes that reflect how we adapt to chronic sleep loss. A better understanding of how the brain responds to and attempts to adapt to lost sleep will help us develop new approaches to reducing the impacts of chronic sleep loss on people.