Humans in their adult years compared to most other species don’t usually nap. Napping is part of the sleep cycle of infants and children, and is quite common in the elderly population. There is a natural and biological propensity to nap during the day. This is due to a dip in the circadian rhythm of the body – the 24 hour sleep wake cycle that is determined both by the daylight cycle, and by the body’s internal 24 hour cycle. (By the way circadian (from the latin “circa” and