The Circadian Rhythm and SAD

Circadian rhythm disorders are disruptions in a person’s circadian rhythm – a name given to the “internal body clock” that regulates the 24-hour cycle of biological processes in animals and plants.

The circadian rhythm is usually disturbed by pregnancy, time zone changes, medications, shift work, depression, or changes in your routine.

Depressives are notorious for being circadian out of sync – feeling sleepy or alert, warm or cold, hungry or without appetite, at the wrong times of day or night – as if they were jet lagged several hours.

Research suggests that for many depressives, the timing of bright light therapy is key, as if it were pushing or pulling their circadian clocks into sync. Indeed, for other conditions, tweaking the circadian clock is the express purpose of light therapy.

Seasonal Affective Disorder is also a symptom of a disrupted circadian rhythm.  Doctors fear that if a person’s biological clock is disrupted for too long, it could lead to cardiovascular disease, and a depreciation of melatonin could increase a patient’s risk of cancer.