Live-in grandparents helped human ancestors get a safer night’s sleep. Duke Today, July 12, 2017. A sound night’s sleep grows more elusive as people get older. But what some call insomnia may actually be an age-old survival mechanism, researchers report. A study of modern hunter-gatherers in Tanzania finds that, for people who live in groups, differences in sleep patterns commonly associated with age help ensure that at least one person is awake at all times. Picked up by The New York Times, CBS News, New Scientist, Discover Magazine, Science, Huffington Post, Daily Mail, Cosmos, The Guardian, BBC News, Mental Floss, Popular Science, Reader’s Digest, USA Today and The Telegraph.