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Sleeping (or Not) by the Wrong Clock

Thursday April 22, 2010

Michael Terman

AARPBulletintoday - Despite his best efforts, Cliff, 28, could not get to sleep until about 7 a.m. It had been this way since he was a teenager. He was a healthy and successful young scientist — except that he didn’t arrive at the lab until 5 p.m., just as his co-workers were preparing to leave.

Although he got his work done by pulling all-nighters, he became isolated from the group. Sleeping pills didn’t work. Nighttime alcohol bouts got him to sleep sooner, but only by two to three hours — a bummer on many levels. Significantly, Cliff was not depressed.

George, a 34 year-old paralegal, had a much more common experience. He could rarely sleep until 1:30 a.m. Inured to sleeping pills, he would get into bed at midnight, hoping for the best. He had to be awake at 7:30 in order to make it in by 9, but it was a losing battle. Almost always late, he remained foggy until afternoon, and suffered headaches. Unlike Cliff, George was mildly depressed.

Cliff and George, whose names have been changed here to protect their privacy, are two of hundreds of patients we’ve treated at the Center for Light Treatment and Biological Rhythms at Columbia University Medical Center (where I serve as clinic director), and in research trials supported by the National Institute of Mental Health and the Sleep Research Society Foundation at the New York State Psychiatric Institute (where I have been a principal investigator).

Both Cliff and George were treated using chronotherapeutics — methods designed to reset the internal circadian clock.[1], [2] George was dealing with sleep onset insomnia, a problem for millions of people. We inferred clinically that his circadian clock signal for sleeping was delayed relative to local time. 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 [3] that helps determine when light exposure will be most effective for syncing your circadian rhythm with external reality.

George began therapy at 8 a.m every day with 30 minutes of 10,000 lux bright light. [4] This had no effect. But when we switched the timing to 7:30, he immediately started getting to sleep an hour earlier, by 12:30 a.m. However, he began waking up far too early, before 6 a.m. This indicated an overdose of light. When we reduced light exposure to 15 minutes, still at 7:30 a.m., he began falling asleep at midnight and waking up just before alarm (a few minutes before the scheduled light exposure). Within a week of starting treatment, his depression lifted, he was more alert in the morning and his headaches vanished. Lesson learned: just as with drugs, light therapy needs to be individually dosed, which may require a clinician’s guidance.

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