Definition: Chronotherapy refers to the use of circadian or other rhythmic cycles in the application of therapy. Examples of this are treatments of psychiatric and somatic diseases that are administered according to a schedule that corresponds to a person’s rhythms in order to maximize effectiveness and minimize side effects of the therapy.
Chronotherapy is used in different fields, examples of this are the treatment of asthma, cancer, hypertension, and multiple types of depression, among others seasonal affective disorder and bipolar disorder. Apart from the clinical applications, chronotherapy is becoming increasingly popular in non-clinical settings, for example on the work floor, where it is used to increase productivity and performance.
*Methods of pharmaceutical chronotherapy:
*Imitative/Mimetic: Imitating the natural changes in a certain substance in the body.
*Preventive/Precautionary: Taking medicines at the moment that they are most necessary, for example taking hypertension medicine at the time of day that the blood pressure is rising.
Chronotherapy is a successful treatment of diseases may depend on the time of day or month that a medicine is taken or surgery performed. Asthma and arthritis pain are examples of conditions now being treated by the clock or calendar.
How our bodies marshal defenses against disease depends on many factors, such as age, gender and genetics. Recently, the role of our bodies’ biological rhythms in fighting disease has come under study by some in the medical community.
Our bodies’ rhythms, also known as our biological clocks, take their cue from the environment and the rhythms of the solar system that change night to day and lead one season into another. Our internal clocks are also dictated by our genetic makeup. These clocks influence how our bodies change throughout the day, affecting blood pressure, blood coagulation, blood flow, and other functions.
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Some of the rhythms that affect our bodies include:
*Ultradian, which are cycles shorter than a day (for example, the milliseconds it takes for a neuron to fire, or a 90-minute sleep cycle)
*Circadian, which last about 24 hours (such as sleeping and waking patterns)
*Infradian, referring to cycles longer than 24 hours (for example monthly menstruation)
*Seasonal, such as seasonal affective disorder (SAD), which causes depression in susceptible people during the short days of winter.
Chronotherapy (sleep phase)
In chronotherapy, an attempt is made to move bedtime and rising time later and later each day, around the clock, until the person is sleeping on a normal schedule. This treatment can be used by people with delayed sleep phase disorder who generally cannot reset their circadian rhythm by moving their bedtime and rising time earlier.
Here’s an example of how chronotherapy could work over a week’s course of treatment, with the patient going to sleep 3 hours later every day until the desired sleep and waketime is reached. (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.)
Day 1: sleep 04:00 to 12:00
Day 2: sleep 07:00 to 15:00
Day 3: sleep 10:00 to 18:00
Day 4: sleep 13:00 to 21:00
Day 5: sleep 16:00 to 00:00
Day 6: sleep 19:00 to 03:00
Day 7 to 13: sleep 22:00 to 06:00
Day 14 and thereafter: sleep 23:00 to 07:00
While this technique can provide temporary respite from sleep deprivation, patients may find the desired sleep and waketimes slip. The desired pattern can only be maintained by following a strictly disciplined timetable for sleeping and rising.
Other forms of sleep phase chronotherapy:
A modified chronotherapy 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.
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.
Chronotherapy is not well recognized in the medical community, but awareness is increasing. The implications are broad in every area of medicine.”
The safety of chronotherapy is not fully known. 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.
Chronotherapy has been known to cause non-24-hour sleep–wake disorder in at least three 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.