I know some people who can do this!

The common swift (as well as some other birds and some aquatic animals) is capable of unihemispheric slow-wave sleep: one half of the brain is asleep while the other half remains alert (including an open eye). This makes long, non-stop migrations possible. pic.twitter.com/zmZAnPem8k

— Fermat's Library (@fermatslibrary) January 2, 2019