Many people find this comfortable because your body naturally needs to regulate its temperature as you fall asleep.
As bedtime approaches, core body temperature normally begins to drop while blood vessels in the hands and feet dilate, allowing heat to escape. This process is associated with sleepiness and faster sleep onset.
Putting one foot or leg outside the covers may therefore:
- Let a little extra heat escape through the exposed skin.
- Prevent you from feeling overly warm or “trapped” under heavy bedding.
- Provide a comfortable temperature balance between the covered and uncovered parts of your body.
Interestingly, research shows that warming the feet can also promote sleep, because warming the extremities increases blood flow and helps redistribute heat away from the body’s core. So the key isn’t necessarily that a cold foot makes you sleepy—the important factor is finding a comfortable thermal balance that allows your body to regulate heat.
In short, the one-leg-out position is probably a simple personal thermoregulation strategy, rather than a special sleep technique that everyone needs to use.
