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Bright light therapy is used to manage circadian rhythm disorders such as delayed sleep phase syndrome (DSPS), a condition which shifts the normal sleeping pattern outside what is considered the social norm. People who have DSPS generally don't fall asleep until several hours after midnight and have trouble waking up in the morning, making adhering to a normal work or school schedule difficult. However, if allowed to follow their own schedules, their quality of sleep is otherwise normal.
Bright light therapy is used to gradually shift sleeping patterns to what we consider normal. For treatment, the timing of light exposure is critical. For DSPS, the light must be delivered to the retina as soon after spontaneous awakening as possible to achieve the desired effect. People have also reported success with lights that turn on shortly before awakening, to simulate dawn. Morning use may also be effective for non-24-hour sleep-wake syndrome, while evening use is recommended for advanced sleep phase syndrome. There is less data about the effectiveness of light therapy for advanced sleep phase syndrome than there is for morning light exposure in delayed sleep phase syndrome.
This technique—also called phototherapy—uses appropriately timed exposure to light to help delay the patients biological clock. The source of light could be artificial, such as a full spectrum lamp at 10,000 lux or portable visor at lower light intensity or, when reliably available at the right time, natural outdoor light. Longer properly timed light exposure is better, with recommended exposure duration of 30-90 minutes. The ideal timing of the light exposure depends on the best approximation available of the persons circadian clock.
The sleep specialists works with the patient to decide on the timing of the light exposure based on patients symptoms and life circumstances. The specialist may start by recommending light exposure take place shortly before the patients usual time of spontaneous awakening.
The specialist helps the patient slowly shift the sleep period to an earlier time. After the desired sleep schedule is attained patients should maintain a fixed rise time (even on weekends and vacations) and ideally continue to use morning light exposure on most mornings, though the duration of light exposure can be shorter. Specialists often recommend using dim lights in the evening in conjunction with bright light exposure in the morning during the advancement of the sleep schedule.
For maintenance, some patients continue the treatment indefinitely, while some reduce their daily treatment to 15 minutes. Others may use the lamp a few days a week or even every other or third week. The degree of success is different for each patient. Light therapy generally adds a little extra time to the morning routine. If you have a family history of macular degeneration, you should consult with an eye doctor prior to starting bright light therapy.