She began organizing promotions and an advertising campaign and writing for the company newsletter. The food we eat, our health and level of activity, even the time of day can play a role in how we feel. Many people have a postlunch dip, when their speed of reaction is slowed, their tendency to fall asleep is higher, and their performance may be impaired. Rusak says it's normal for humans to have low body temperatures in the early morning, when many physiological functions are at a low ebb. A person tends to be in a bad mood if awakened at that time.
Moods improve as body temperature rises during the day.
For some people this dip and rise occurs earlier in the morning. Their temperatures rise later. Stanley Coren, a University of British Columbia psychology professor and author of Sleep Thieves, says too little sleep can play havoc with our emotions. When you acquire a sleep debt, your mood plummets. And the bigger the debt, the more significant the deterioration in mood.