Grant: CIHR New Investigator

The causes of sleep disorders are still not clearly understood. Disorders of sleep are however very frequent, cause threatening risks of accidents, and impair productivity and quality of life. I propose to use sophisticated neuroimaging techniques to identify the brain regions responsible for disorders of sleep. This approach will particularly be applied to the study of specific sleep disorders responsible for sleepiness during the day: narcolepsy and idiopathic hypersomnia. Patients with narcolepsy inappropriately fall asleep during the day for short periods of time without being able to resist the urge to sleep. Narcolepsy is often accompanied by sudden episodes of muscle weakness triggered by emotions and termed cataplexy. Sleepiness in narcoleptic patients with cataplexy is related to a lack of a substance in the brain called hypocretin. However, some patients with narcolepsy never experience episodes of cataplexy. Idiopathic hypersomnia closely resembles narcolepsy, and also involves daytime sleepiness but no cataplexy. There is no lack of hypocretin in patients with narcolepsy without cataplexy and idiopathic hypersomnia, and their causes are thus poorly understood. Finally, all these patients with daytime sleepiness also have a poor quality of sleep at night with frequent awakenings. The reasons for such sleep disruption remain unclear. My objective is to use brain imaging during wakefulness and sleep in narcolepsy and idiopathic hypersomnia: 1. to elucidate the causes of daytime sleepiness, 2. to understand the causes of sleep disruption in these patients. This modality of investigation will be further applied to other sleep disorders, such as sleepwalking, and to sleep disturbances in neurological disorders. Identifiying the brain regions responsible for sleep disorders will not only improve our understanding of the causes, but will also allow to better diagnose, better predict the evolution, and ultimately better treat these disabling disorders.