A new study has explained why sleep is so much harder to come by if you’re in a new place – mostly because half of your brain isn’t actually asleep.

The ‘first night effect’ occurs when you are not used to the location you are sleeping and as a result, the left side of the brain doesn’t ‘switch off’ correctly. This phenomenon is well-known to Experimental Psychologists and researches who study sleep, and frequently, data from the first night of studying someone’s sleeping patterns is discarded. Masako Tamaki, of Brown University, conducted extensive research into this well-known phenomenon to understand why it was occurring.

Scanning the brains of 11 healthy volunteers , Tamaki tracked the slow waves of participants during sleep over two periods, a week apart. Slow wave are low-frequency patterns of brain activity which reflect how deep a sleep someone is in. The study found that during the first sleep, the activity of slow waves in the left hemisphere was much weaker, suggesting that the left side of the brain was more active than the right. On the second sleep, once the subject became more familiar with the surrounding, slow wave activity in the left hemisphere was much higher, matching the right.

The greater the slow wave activity in a brain, the quicker a person falls asleep. Biological Sciences applicants should consider how sleeping patterns are adaptive to different animal species, such as how some birds and marine mammals put half of their brain to sleep in order to stay vigilant.

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