Poor sleep is often regarded as a modern affliction linked to our sedentary lifestyles, electric lighting and smartphones on the bedside table.
However, new research suggests that fitful sleep could be an ancient survival mechanism designed to guard against nocturnal threats. The study, which tracked the sleep patterns of a modern-day hunter-gatherer tribe in northern Tanzania, found that frequent night-time waking and differing sleep schedules between the young and old ensured that there was nearly always at least one tribe member awake.
