Recommended Reading: Biological Clocks: Your Owner's Manual.

Clinical Proof :

Dawn Simulators use your body's natural response to sunrise and sunset to help synchronise your circadian rhythm (sleep/wake pattern). Using a Bodyclock will help regulate your melatonin cycle to keep levels high at night, making you sleepy, and low in the day, keeping you alert. This means you sleep better at night, and feel more energetic during the day.

One of the major causes of SAD is a circadian rhythm that is out of sync, which happens especially in the winter in northern countries. The Bodyclock or natural light alarm clock helps to get your sleep/wake pattern or circadian rhythm back in sync. Clinical studies have shown dawn simulation to have a dramatic effect in relieving the symptoms of SAD* as well improving mood, energy, productivity and the quality of sleep and awakening.**

*Biol Psychiatry. 2001 Aug 1;50(3):205-16
**Acta Psychiatr Scand 1993 Jul; 88 (1):67-71