Fingers warm up before sleep, not just at night but anytime a person feels sleepy. This finding is from a new study, the first to examine the rise in finger temperatures before sleep for a prolonged, 45-hour time period.
As the body prepares to sleep, the body’s core temperature lowers, causing extremities such as fingers to warm up as the heat is dissipated throughout the body. The increase can be as much as three degrees centigrade, according to the study.
Fourteen people took part in the study, which lasted slightly more than two days. Participants were confined to a laboratory and monitored with electrodes to measure skin temperatures and detect the beginnings of sleep.
Their activity was limited to reading, playing board games, watching videos and talking and the room temperature was kept at a constant level.
Results indicated that about 10 minutes before participants began to feel sleepy, finger temperature rose. The increase occurred regardless of time of day, though researchers noted that temperatures were higher at night than during the day.
Journal of Sleep Research 2002;11:1-8
An interesting observation. You could test these observations for yourself and see if you get the same results.