Even though research on sleep goes back to the mid part of the Twentieth century, we still know very, very little about sleep. One area that has been extensively studied are the cycles of sleep and wakefulness (beta, alpha, theta and delta) but even here new research is focusing scientists to re-think how they characterize sleep and consciousness. Pay attention to the “sleep myths” that Foster shatters, as well as the relationship between sleep and mental health.

Why you should listen:

Much as your ear does double duty (balance plus hearing), Russell Foster posits that the eye has two jobs: creating vision, but also — as a completely separate function — managing our perception of light and dark, providing the clues that our circadian rhythms need to regulate sleep-wake cycles.

The research on light perception hits home as we age — faced with fading vision, we also risk disrupted sleep cycles, which have very serious consequences, including lack of concentration, depression and cognitive decline. The more we learn about how our eyes and bodies create our sleep cycles, the more seriously we can begin to take sleep as a therapy.

Who is he:

He and his team at the University of Oxford are exploring a third kind of photoreceptor in the eye: not a rod or a cone but a photosensitive retinal ganglion cell (pRGC) that detects light/dark and feeds that information to the circadian system. As Foster explains: “Embedded within our genes, and almost all life on Earth, are the instructions for a biological clock that marks the passage of approximately 24 hours.” Light and dark help us synchronize this inner clock with the outside world.


  1. What evidence does Foster present that: “Sleep is the golden chain that ties health and our bodies together.”
  1. Think about the light bulb. What was life (at least life at night) like before its invention? How has our night time world changed as the result of this one single invention?
  1. According to the presentation, why do we sleep?
  1. Discuss the effects of sleep deprivation.
  1. You might want to try a little experiment on sleep deprivation, using yourself (and perhaps some friends) as subjects. Stay awake for a longer than usual period of time (2 days or so). Record observations every few hours (you could rate your mood, or see how you perform memory tasks or other cognitive functions). Summarize your results and share them with others. Was your experience unique to you or do others report similar results?
  1. Describe the relationship between sleep disturbance and mental illness. In your answer, discuss whether the evidence is strong enough to show a causal relationship (as opposed to a correlation).

Making Connections:

Why do we dream? with Amy Adkins

“What would happen if you didn’t sleep? with Claudia Aguirre


Why do we sleep? with Russell Foster


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