Research

Circadian Rhythms Research at Simon Fraser University

Research in the circadian rhythms laboratory at Simon Fraser University seeks to understand the functions and neurobiological mechanisms of circadian clocks and sleep in mammals.

1. Food Availability and Circadian Rhythms
   Circadian clocks are synchronized to local time by sensitivity to environmental time cues (known as ‘zeitgebers’, in chrono-lingo). Light-dark cycles are a dominent zeitgeber for most species, but food intake also plays a critical role setting the phase of behavioral and physiological rhythms. A major part of our work is directed to understanding the brain mechanisms by which food synchronizes behavioral rhythms, enabling animals to anticipate regular daily mealtimes, and to remember the time and place of food availability.
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2. Regulation of Circadian Rhythms by Behavioral State
   Behavioral arousal induced during the usual sleep period can reset the circadian clock in at least some mammalian species, thereby shifting the daily sleep-wake cycle. We are conducting studies to identify the neural pathways and neurochemicals that mediate this effect of behavioral state on the circadian clock.
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3. Mechanisms of Sleep and Consequences of Sleep Loss
   Why we sleep remains controversial. Sleep loss impairs waking functions and has adverse effects on neural and physiological processes. We showed that sleep restriction in rats inhibits the production of new neurons in the hippocampus, a brain region critical for learning and memory. Current studies are investigating the mechanisms mediating this adverse consequence of sleep restriction.
   
   
4. Sleep Deprivation in Humans: Consequences and Countermeasures
   Circadian regulation of behavioral state presents an ongoing challenge for people whose work entails night shifts or jet travel. The most significant consequences of circadian regulation under these conditions are impaired nighttime alertness and insufficient daytime sleep. We are currently evaluating light as a countermeasure for performance decrements in driving performance after a simulated nightshift.