The circadian rhythm is the body’s internal clock that helps you sleep at night and wake in the mornings. Your internal clock also determines eating patterns and allows for hormone production, brain wave activity, and other biological activities. Inadequate sleep causes circadian rhythm disruptions that will make it difficult to fall asleep at night, or make you sleepy too early in the day. Disruptions will also cause irritability, loss of appetite, mood swings, general discomfort, and impaired decision making.