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What Is Chronotherapy? Benefits of Chronotherapeutic Treatment for Sleep Disorders and Depression

Chronotherapy is usually a non-medical treatment that shifts the sleep-wake cycle to the desired time. Chronotherapy may help beat mental, sleeping, and eating disorders.

Chronotherapy is a therapeutic technique, which, instead of using drugs, uses your body’s circadian rhythm or biological clock to make changes in the sleep/wake cycle and daily exposure to light. Chronotherapy aims to reset your unregulated circadian rhythm to a normal cycle of sleeping/waking, which can also play a role in optimizing medical treatments such as chemotherapy.  

In some cases, chronotherapy may also refer to administering medicines in alignment with your biological clock to get optimal results while decreasing adverse physical effects (referred to as treatment scheduling).

Doctors may use bright light exposure therapy to manage disorders of the circadian rhythm, including delayed sleep phase syndrome (DSPS). It is difficult for people with DSPS to fall asleep until the hours of the early morning, and as a result, they may have trouble waking up in the morning. This may also make it difficult for them to adhere to their normal school or work schedule. For the treatment of DSPS, doctors deliver bright light to the retina as soon as possible after spontaneous awakening. Turning on lights just before waking may also prove to be successful as it simulates dawn.

Chronotherapy can also use a form of phototherapy or light therapy that involves exposure to bright lights daily, and you may administer it at your home using a fluorescent lightbox. The standard/usual protocol is to use 10,000 lux of light intensity for half an hour every day during the morning (early) hours for up to six weeks. You should start to see a difference within one to three weeks. The antidepressant effects of light therapy include the modulation of catecholamine and serotonin systems and alteration of biological clocks.

You may use light therapy to treat the following conditions:

  • Seasonal affective disorder (SAD)
  • Jet lag
  • Depression (not seasonal)
  • Sleep disorders
  • Dementia
  • Difficulty adjusting to a night work schedule

Individuals generally tolerate light therapy well, but in some cases, the following side effects may occur: eye strain, nausea, sedation, agitation, irritation, headache, and euphoria, mania, agitation, or hyperactivity related to bipolar disorder.

Another type of chronotherapy is sleep deprivation therapy (SD). Individuals are kept awake or sleep-deprived for an extended duration of time. The total sleep deprivation may last up to 40 hours, while partial sleep deprivation may allow three to four hours of sleep every night. Doctors typically use SD two to four times during one week with complete sleep deprivation often mixed with normal sleep or partial SD.

One of the limitations of SD is that it is difficult to maintain longer than several weeks. There is a rapid relapse of the condition after its discontinuation. One of the common adverse effects of sleep deprivation is sleepiness during the daytime. The only contraindication to SD use is epilepsy, as sleep deprivation may significantly increase the risk of seizures.

Doctors may use chronotherapy with phase advances (progressive) around the clock until you reach the desired time to go to bed. Exposure to bright light (greater than 1,000 lux) during the morning hours or administration of melatonin during the evening hours results in phase advances, whereas doing the opposite results in phase delays.

This kind of chronotherapy aims to reset and stabilize the circadian rhythms of individuals. It combines repeated sleep deprivation cycles, sleep phase advance, and exposure to bright light during the morning hours.

The American Academy of Sleep Medicine recommends chronotherapy to treat sleep and circadian rhythm disorders. It may help individuals with delayed sleep phase disorder who aren’t able to reset their biological clock by making their rising time and bedtime earlier.

Chronotherapy has shown efficacy in the treatment of mental disorders such as depression. It is well-tolerated by people with depression as it has a quick treatment response and produces fewer side effects. Overall, chronotherapy is recommended over other treatments such as antidepressants, psychotherapy, and light or exercise therapy alone after five to seven days.

Chronotherapy may be effective in both bipolar and unipolar depression, and the response may appear within one week. In comparison with routine treatments, including medicine, exercise, or talking therapy, chronotherapy has the additional benefits of quick treatment response along with a greatly favorable profile of side effects. Furthermore, there is no remarkable shift to hypomania in people with bipolar disorder after they receive chronotherapy. But further work needs to be done to bring uniformity in the usage of chronotherapy in treating major depression.

But the chronicity and severity of symptoms of depression may play a vital role in response to treatment, and the latter may be reduced in cases that are resistant to treatment.

There are no risks related to chronotherapy, but the effectiveness of treatment depends on respecting the exact timing and modalities of the therapy. At times, it is challenging to reproduce the identical conditions for light treatment at home, for example, which has previously been carried out in a clinic.

Chronotherapy is a type of therapy that uses the body’s natural cycles and rhythms. Its goal is to increase the efficiency of medical therapies by incorporating the circadian rhythm or biological clock of your body. The American Academy of Sleep Medicine recommends chronotherapy in the treatment of sleep and circadian rhythm disorders. Apart from chronotherapy for sleep, it has been found to improve treatment in many diseases, including asthma, epilepsy, rheumatoid arthritis, cancers, and cardiovascular diseases. The intervals of sleepiness and alertness in each person are different. Therefore, each specific person must have personalized chronotherapy treatment even if, on average, a particular time is shown to be better for the majority of people. The comparatively low number of clinical trials on chronotherapy has become a hurdle in making advancements in this field.


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