Iowa Sleep Blog

Human Clock

Monday, October 17, 2016

Everyone has an internal clock called the suprachiasmatic nucleus (or SCN for short).Like all clocks it turns on and off-- resulting in periods of wake and sleep.

Some clocks are delayed. This genetic condition is called Delayed Sleep Phase Syndrome (DSPS). It causes a problem. The individual can’t get to bed at a regular time and can’t get out of bed at a regular time.

DSPS becomes obvious in the teens or 20s. Sleep is often impossible before 2am and waking is required at 6am due to work/school schedules. Sleep deprivation occurs. Sleepiness results.

The presentation is usually a young person who was an excellent student. Now grades are dropping. Excessive sleepiness in class occurs. Parents worry. Is he/she lazy or on drugs? The individual affected can’t understand what’s going on. Not uncommonly secondary depression results.

There are two ways of treating DSPS. One is to modify the sleep/wake scheduled to match the delayed clock timing. DSPS Adults find working a 2nd shift helps. The 2nd shift more normally matches the body clock timing. Bed time is later and sleeping in the morning is possible. If you find a great 2nd shift job, and have a family situation that fits this pattern – excellent. Usually this is not the case.

The second treatment method changes the clock. This therapy changes the firing pattern. The target is to match clock timing to that of the general society. It uses light and melatonin. Timing of light and melatonin is critical. Using them at the wrong time can make DSPS worse.

The diagnosis of DSPS is based on history and actigraphy. The actigraph is an exotic motion detector which tells movement—not sleep. Movement is used as a surrogate for sleep—the body is usually inactive during sleep and active when awake. Thus --over a period of two weeks-- the sleep and wake cycle can be determined. There are no needles. The actigraph is used at home. It looks and works much like a Fitbit, but it collects more medical information.

Diagnosing DSPS is important in the formative years of the teens and 20s. Getting good grades is important for future success and happiness. It’s not fun to be sleepy.

Written by Steve Zorn, MD, Board Certified Sleep Medicine Physician and Medical Director of Iowa Sleep

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