The circadian reset. What most parents do backwards.

In the second week of August every year, the calls to the clinic increase. Not dramatically — a quiet uptick, the kind that only becomes visible when you track it over several years. The presenting concern is almost always the same: my child cannot fall asleep before eleven, and cannot wake in the morning without a fight. Parents describe this as a behaviour problem, a discipline problem, a summer that has gone on too long. What I see is a circadian system that has drifted.

The circadian clock — the internal timekeeper housed primarily in the suprachiasmatic nucleus of the hypothalamus — is anchored to the environment by a small number of signals, the most powerful of which is light. In summer, with no school schedule to enforce a fixed wake time, this clock drifts. Not randomly: it drifts later. Children fall asleep later because the evening light suppresses melatonin later. They wake later because nothing is pulling the system back. After eight weeks of this, the clock is running ninety minutes to two hours behind where it needs to be for the first day of school.

This is not a character problem. The child who cannot wake for school at the start of September is not lazy or defiant. Their circadian clock is genuinely set to a different time. The question is how to move it — and this is where most parents make the error that brings them to my clinic.