I was curious: thecut.com/…/sleep-hack-keep-one-foot-outside-you…

TL; DR: Our bodies cool down when sleeping, feet can help regulate temeprature, so we may be able to initiate sleep better/quicker using our feet to cool down.

There is no study in the article; it’s speculation by “Natalie Dautovitch, a spokesperson for the National Sleep Foundation and a psychology professor at the University of Alabama”.