Researchers from Wits University teamed up with the NGO Elephants Without Borders and the University of California to use a “scientific Fitbit” to study the sleeping patterns of elephants in the wild.
The exercise was developed to determine whether or not elephants tend to sleep less than smaller animals, as most large animals do.
The research was conducted in the Chobe national Park in Botswana and led by Prof Paul Manger, Dr Nadine Gravett and Dr Adhil Bhagwandin from Wits.
“We reasoned that measuring the activity of the trunk, the most mobile and active appendage of the elephant, would be crucial, making the reasonable assumption that if the trunk is still for five minutes or more, the elephant is likely to be asleep,” said Manger.
The team outfitted two matriarch elephants, noting when they used their trunk by an implanted activity data logger, when they moved around and – by installing a GPS collar with a gyroscope around their necks – where and when they were lying down to sleep.
The main finding of the study, recently published in the journal PLOS ONE, was that the two matriarch elephants slept only two hours per day on average, and this sleep occurred mostly in the early hours of the morning, well before dawn.
“The data also indicates that environmental conditions (temperature and humidity, but not sunlight) are related to when the elephants fell asleep and when they woke up (which happens well before dawn),” says Manger. “This finding is the first that indicates that sleep in wild animals is likely not to be related to sunrise and sunset, but that other environmental factors are more crucial to the timing of sleep.”
The research also found that wild elephants could sleep while standing up, or while lying down. Lying down to sleep only happened every three or four days and for about an hour, and it is likely that when the elephants were lying to sleep were the only times they could go into REM, or dreaming, sleep, meaning elephants possibly don’t dream on a daily basis like we do, but may dream only every few days.
Lastly, the team found that the two elephants, when disturbed by such things as predators, poachers, or a bull elephant, could go without sleep for up to 48 hours, and following the start of the disturbance would walk up to 30 km from where the disturbance occurred. This put a great deal of distance between the elephant herd and any source of danger, but at the expense of a loss of a night’s sleep.
“Understanding how different animals sleep is important for two reasons. First, it helps us to understand the animals themselves and discover new information that may aid the development of better management and conservation strategies, and, second, knowing how different animals sleep and why they do so in their own particular way, helps us to understand how humans sleep, why we do, and how we might get a better night’s sleep.”[Image – CC 0 baluda]