Sleep is one of those things that most of us do not think about that much. It is just a natural part of our day, or night most of the time. We go through the day with the understanding that at the end we will drift off into a slumber and that we will wake in the morning ready for a new day, but what actually happens while we sleep?
For one, our body temperature changes during the night. Just before we drift off, our body heat will dissipate by a degree or two, which some researchers believe helps us go to sleep. Once we have gone to sleep, our body temperature will remain at a few degrees below our normal waking temperature, meaning that we will use less energy, which is theorised as one of the main functions of sleep- as an energy saving device during the least fruitful hours.
During non-REM sleep, our body temperature will stay at about one or two degrees below normal, but when we enter REM sleep our body temperature drops to its lowest. Generally we are curled up under a blanket when this happens so we do not lose too much heat but this is the time when we are most vulnerable to the cold at night.