According to NHS Choices website, symptoms of insomnia include:
- Difficulty falling asleep
- lying awake for long periods at night
- waking up multiple times during the night
- waking up early in the morning and not being able to get back to sleep
- having sleep that is not restful or restorative
- difficulty napping during the day, despite feeling tired
- feeling tired and irritable during the day and struggling to concentrate
A new study from researchers at the Duke University, South Carolina say that it may be survival instinct.
Modern hunter-gatherers of the Hadza tribe in Tanzania, were observed over three weeks.
The Hadza were found to operate a shift pattern at night, where one member of the tribe was always awake.
During three weeks of observation, there were only 18 minutes where all 33 members of the tribe were asleep simultaneously.
Speaking to the Evening Standard, one of the authors associate professor Charlie Nunn said:
A lot of older people go to doctors complaining that they wake up early and can’t get back to sleep.
But maybe there’s nothing wrong with them. Maybe some of the medical issues we have today could be explained not as disorders, but as a relic of an evolutionary past in which they were beneficial.