National Sleep Foundation. "Some people find that sleeping with a hand or foot outside of the bed covers can help with body cooling, as heat dissipates quicker through the body extremities."
There's nothing really special about your feet that makes them a good body part to air out, says Winter, but since you can't exactly sleep with your knees or stomach outside the covers, the extremities are a convenient choice.
And as for the claim that heat messes with your sleep, that's definitely true. "Generally, cool environments lead to a deeper state of sleep and less awakening during the night," she says.
The sticking your feet out technique may not be for everyone, but if your sleep is suffering from the heat, it's one of several options you can try. You can also get cool gel pads or pillows to keep your head and the rest of your body at the right temperature☺, Dr. Winter suggests....
Since sleep affects so many areas of your life, it's worth spending some time to figure out what can get you the most restful sleep
— hope you will like and upvote my post