Resetting Your Sleep Clock with Chronotherapy

New York Times. 
People sleep best when the internal clock is in sync with the workday rest/activity cycle. When there is a mismatch, the likely results are insomnia, depressed mood and daytime fatigue.

An unbalanced circadian rhythm can be returned to equilibrium through the application of light to a sleeper’s retina near the end of a person’s “internal night.” Internal night? Yes — it may be night outside, but if your circadian clock is not prepared for sleep, internal night may not start until late and last well into morning. Biologically, it coincides with the secretion of melatonin by the brain’s pineal gland. It is difficult to know where your internal night lies if you artificially force sleep earlier, for example with sleeping pills. You can estimate internal night with a quick chronotype questionnaire that helps determine when light exposure will be most effective for syncing your circadian rhythm with external reality.

In American psychiatry, chronotherapeutics is a new kid on the block, viewed by some as a counter-intuitive departure from conventional medication. By contrast, in Europe, where it is already well established, it is seen as compatible with medication and a means for expediting improvement with fewer residual symptoms. Residual symptoms are harbingers of relapse. To protect our patients, we should be pulling out all the stops.