Another factor that influences when and how well we sleep is our body temperature.
The rise and drop of core body temperature is one of the mechanisms for our body to produce the feelings of being awake or being tired.
Body temperature is the lowest in the early morning hours, starts rising before awakening, peaks in the early evening, and begins declining in the late evening. This cycle is closely tied to alertness-sleepiness. There is a small dip in body temperature between 1 and 4 pm. We often think that the drowsiness that occurs after lunch is due to eating, but actually it has more to do with this drop in body temperature. In some countries this mid-day tiredness is recognized and taking a siesta or mid-day rest is an accepted part of the culture. In England, the traditional mid-afternoon cup of tea is another way of coping with this drowsiness.
The body needs to cool down to allow the core temperature of the internal organs, especially the heart and lungs, to slow their rate.
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