Sleep studies have shown that all living beings need periods of sleep to clear toxins from their brains. But while humans may need at least seven hours of shut-eye to be at their best, wild elephants in Africa can apparently get by with about two hours of downtime, making them the lightest sleepers of any mammal. A study by University of Witwatersrand researchers in South Africa collected data by attaching motion detectors to two elephants’ trunks over 35 days, determining that at least five minutes of inaction indicated a period of sleep. The elephants averaged a total of two hours a night, but they’d nod off in four or five short bursts – a pattern known as polyphasic sleep.
You are getting very sleepy:
- The most reliable way to measure sleep is to collect electrical impulses from the brain, but elephants have thick skulls and attaching electrodes would have been too invasive.
- Most of their slumber occurred between 1 a.m. and 6 a.m. The elephants slept in different places every night, and on four occasions they didn’t sleep at all, coinciding with days on which they traveled long distances.
- Each elephant also wore a collar with a gyroscope, which let the researchers know if the animal was standing up or lying down. The elephants each slept lying down on just 10 of the 35 days.