Sleep Dynamics

Humans spend one third of their lives sleeping, and yet only now we are starting to understand why we need to sleep and what are the mechanisms of sleep. Lack of sleep leads to poor performance, risk of accidents, and, in severe cases, disease. Disturbances of sleep and circadian system as appear during shiftwork are particularly dangerous due to their chronic nature, and have been linked to double the rate of accidents and increased risks of diabetes, cardiovascular disease, and cancer. Our key interests in sleep research are to (i) improve understanding of the brain dynamics controlling sleep, (ii) develop interventions reducing sleep and circadian disturbances, and (iii) predict alertness during normal and disturbed sleep-wake cycles.

We have developed the first model of the brainstem ascending arousal system in the brain that governs sleep and wake, and have successfully reproduced a range of normal and sleep-deprived behaviors, including the effects of pharmacological agents (e.g., caffeine, modafinil). To enable study of the circadian disturbances we combined this model with a model of a light-driven circadian oscillator and now address such issues as sleepiness and adaptation during jet lag and shift work (also see We also study EEG dynamics during sleep and have employed the group’s highly successful EEG-generation model to predict sleep-wake signatures in the EEG.

Numerous areas exist for PhD, MSc, or Honors projects, which could include theoretical, computational, experimental, and/or clinical components in cooperation with our collaborators at the Woolcock Institute for Medical Research, the Brain and Mind Research Institute, and elsewhere.
The group now plays a major role in two sleep and alertness research centers:

Sleep spectrum

Our model's prediction of sleep. (a) A diagram showing the states of arousal as predicted from the model. (b) Time course predictions at different states c.f. (a).


  1. Fulcher, B. D., Phillips, A. J., Postnova, S., & Robinson, P. A. (2014). A physiologically based model of orexinergic stabilization of sleep and wake. PloS one, 9(3), e91982.
  2. Postnova S, Postnov DD, Seneviratne M, Robinson PA (2014) Effects of Rotation Interval on Sleepiness and Circadian Dynamics on Forward Rotating 3-Shift Systems. J Biol Rhythms 29 (1), 60-70.
  3. Postnova S, Layden A, Robinson PA, Phillips AJK, Abeysuriya RG (2012) Exploring Sleepiness and Entrainment on Permanent Shift Schedules in a Physiologically Based Model. J Biol Rhythms. 27:91-102.
  4. Puckeridge M, Fulcher BD, Phillips AJK, Robinson PA (2011) Incorporation of caffeine into a quantitative model of fatigue and sleep. J Theor Biol, 273:44-54.
  5. Phillips, A. J. K., and Robinson, P. A., Kedziora, D. J., and Abeysuriya, R. G. (2010). Mammalian Sleep Dynamics: How Diverse Features Arise from a Common Physiological Framework, Public Library of Science – Computational Biology, 6, 31000826, 1-9.
  6. Phillips, A. J. K., & Robinson, P. A. (2007). A quantitative model of sleep-wake dynamics based on the physiology of the brainstem ascending arousal system. Journal of biological rhythms, 22(2), 167-179.