Time for a nap
QI’ve been spending time amongst my hens and I’ve noticed that they sometimes close just one eye for a few seconds at a time whilst the other one is open. There doesn’t seem to be anything wrong with their eyes but I’m curious as to a reason they do this.
AJulie Moore says: Your hens are actually taking a quick nap. Chickens have the ability to sleep with one eye open and the other closed. During this form of sleep, unihemispheric slow-wave sleep (‘USWS’), half of the brain gets a rest whilst the other remains awake and alert for predators.
A chicken’s brain is divided into two hemispheres. Each eye is attached to the opposite hemisphere, i.e. the left eye is attached to the right hemisphere and the right eye is attached to the left hemisphere. Chickens can be asleep and awake at the same time!
USWS enables chickens to sleep and be alert for predators at the same time.
According to scientific studies, chickens are able to make behavioural decisions as to whether they keep one half of their brain awake or allow both halves to sleep. Chickens seem to be able to use USWS at will. When they are sleeping in a more risky situation, they will increase the proportion of their sleep with one eye open and half their brain awake.
Chickens have the ability to sleep with one eye open and the other closed.