Chronotherapy
People who suffer from delayed sleep phase syndrome are generally unable to reset their circadian rhythm by moving their bedtime and rising time earlier. In chronotherapy an attempt is made to move bedtime and rising time later and later each day, around the clock, until these times reach the number of hours of sleep per night an individual needs to be fully functional. According to Michael B. Russo, MD,[citation needed] the number of hours of sleep per night necessary for an individual to be fully functional is still unknown because the function of sleep has yet to be fully determined. Some people claim full effectiveness with only 3–5 hours of sleep per night, while others admit to needing 8 (or more) hours of sleep per night to perform effectively.
While chronotherapy has been successful for some, it is necessary to rigidly maintain the desired sleep/wake cycle thenceforth. Any deviation in schedule tends to allow the body clock to shift later again.
Here's an example of how chronotherapy could work over a week's course of treatment, with the patient going to sleep three hours later every day until the desired sleep and waketime is reached. This technique assumes that an individual can perform effectively with 8 hours of sleep per night. Shifting the sleep phase by 3 hours per day may not always be possible. Shorter increments of 1–2 hours are needed in such cases.[citation needed]
Example:
- Day 1: sleep 4 a.m. to noon
- Day 2: sleep 7 a.m. to 3 p.m.
- Day 3: sleep 10 a.m. to 6 p.m.
- Day 4: sleep 1 p.m. to 9 p.m.
- Day 5: sleep 4 p.m. to midnight
- Day 6: sleep 7 p.m. to 3 a.m.
- Day 7 to 13: sleep 10 p.m. to 6 a.m.
- Day 14 and thereafter: sleep 11 p.m. to 7 a.m.
While this technique can provide temporary respite from sleep deprivation, patients often find the desired sleep and waketimes soon slip, returning them to a state of delayed sleep onset within a few weeks or even days. The desired pattern can be maintained—to a degree—by following a strictly disciplined timetable for sleeping and rising, but all too often this cannot be maintained, as the body returns to its previous pattern of late sleep onset, regardless of when the patient rises.
A modified chronotherapy[1] is called controlled sleep deprivation with phase advance, SDPA. One stays awake one whole night and day, then goes to bed 90 minutes earlier than usual and maintains the new bedtime for a week. This process is repeated weekly until the desired bedtime is reached.
An expanded set of techniques, together called chronotherapeutics, combines light therapy, wake therapy (sleep deprivation) and sleep phase advance therapy. It is particularly useful for inducing rapid, sustained remission in patients with depression. Many of these patients have the late circadian rhythm tendency seen in delayed sleep phase disorders. Indeed, many patients with delayed sleep phase syndrome become depressed. A 2009 treatment manual has been published, Chronotherapeutics for Affective Disorders.[2]
Side effects
Chronotherapy has been known to cause Non-24-hour sleep-wake syndrome in at least 3 recorded cases, as reported in the New England Journal of Medicine in 1992. Animal studies have suggested that such lengthening could "slow the intrinsic rhythm of the body clock to such an extent that the normal 24-hour day no longer lies within its range of entrainment."[3]
Reverse chronotherapy
Sometimes, although extremely infrequently, "reverse" chronotherapy—i.e., gradual movements of bedtime and rising time earlier each day—has been used in treatment of patients with abnormally short circadian rhythms, in an attempt to move their bedtimes to later times of the day. Because circadian rhythms substantially shorter than 24 hours are extremely rare, this type of chronotherapy has remained largely experimental, with very little large-scale study.
References
- ↑ Thorpy et al. in J Adolesc Health Care, 1988;9.
- ↑ Wirz-Justice et al., 2009.
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- Czeisler, C.A., Richardson, G.S., Coleman, R.M., Zimmerman, J.C., Moore-Ede, M.C., Dement, W.C., & Weitzman, E.D. (1981). Chronotherapy: Resetting the circadian clocks of patients with delayed sleep phase insomnia. Sleep, 4, 11–21.
- Wirz-Justice, A., Benedetti, F., Terman, M. (2009) Chronotherapeutics for Affective Disorders: A Clinician's Manual for Light and Wake Therapy. Basel, Karger.
