Why do we Sleep?

Sleep-o-MeterRussell Foster is a circadian neuroscientist at the University of Oxford in Cambridge. He studies sleep and its role in our lives, examining how our perception of light influences our sleep-wake rhythms.

In this TED Talk (below) Foster asks, “What do we know about sleep?”

Not much, it seems, and that’s surprising for something that occupies one-third of our lives. Foster shares three theories about why we sleep:

  1. Energy Conservation (saving calories, unlikely);
  2. Restoration of the body (yes, tied to good health); and
  3. Improving Brain Function, including memory consolidation and enhanced creativity.

He also busts some myths about how much sleep we need at different ages and hints at some bold new uses of sleep as a predictor of mental health.

Light and its influence on the Body Clock

Just as our ears do double duty (balance plus hearing), Foster suggests that the eyes do two jobs too. They create vision and manage our perception of light and dark, regulating sleep-wake cycles and our circadian rhythms.

His team at Oxford is exploring a new kind of photoreceptor in the eye. It’s 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.

Foster explains that, “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 darkness help us synchronize this inner clock with the outside world.

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