The meal times and morning physical exercise contribute to the regulation of circadian clock and, therefore, improve insomnia and fatigue.[28] Exposure to sunlight, especially in the morning, also contributes to the regulation of circadian clock and reduce insomnia.[29] On the other hand, a balanced diet and adequate exercise help to improve body composition and increase muscle mass, which in turn improve metabolism and thus facilitate a more active life with increased exercise and less fatigue. The gene discussed is CLOCK; the disease is insomnia.