Like clockwork

If you want to sleep well, get a dog. Those early morning walks provide regular exercise, which we know is good for sleep. But as Russell Foster, a British neuroscientist who specialises in the study of circadian rhythms, points out, they also expose you to the early morning light we all need to keep our internal body clocks – most of which run at about 24 hours and 10 minutes – aligned or “entrained” with the 24-hour day.

The result: better, more regular sleep. “People who own a dog have been shown to have better sleep, and you might think, ‘What’s that all about?’ Of course, it’s because they have to take their dog out in the morning and that’s where they get their photon shower – their entraining light,” says Foster, author of Life Time, which looks at how our bodies are governed by a 24-hour circadian clock.

Without that early morning exposure to light – preferably at least 30 minutes outside where light is much brighter, although sitting inside by a window is acceptable if it’s raining – our internal clocks would eventually become misaligned with the external clock. We would start to go to bed about 10 minutes later every night and eventually our sleep-wake pattern would be