Bright-light therapy is a procedure that is used, among other things, to treat seasonal depression and forms a subfield of light therapy. This so-called winter depression is a condition caused by a daily lack of sunlight. In healthy people, daylight has a direct influence on the internal clock and thus determines the biorhythm. This clock is located in the central nervous system (brain), in the hypothalamus, and is called the nucleus suprachiasmaticus. It is a nucleus area (collection of nerve cell bodies) whose cells control the pulsatile release of the hormone melatonin during darkness. The cells of the nucleus suprachiasmaticus are connected to the retina (retina) of the eye by nerve fibers and can thus register light conditions. The hormone melatonin is the timer of metabolism and has a circadian, sleep-promoting effect. The synthesis (production) of melatonin takes place from serotonin, a biogenic amine that, among other things, increases the sense of well-being. In the absence of light, the concentration of melatonin increases while the concentration of serotonin decreases. This constellation can trigger depression, which occurs, for example, in the winter months when daylight does not last long enough and is known as seasonal affective disorder (SAD). These are seasonally linked depressive phases of greater or lesser severity, characterized by the following symptoms:
- Fatigue
- Increased need for sleep
- Listlessness
- Difficulty thinking and concentrating
- Libido weakness
- Cravings
- Weight gain
The lack of light that underlies this condition can be addressed with bright light therapy.
Indications (areas of application)
- Subsyndromal SAD (SAD with mild depressive mood).
- Mild non-seasonal depression
- Vegetative disorders in shift workers – e.g. sleep disturbances.
- Jet lag
- Bulimia nervosa – binge eating disorder characterized by binge eating followed by drastic measures to reduce weight.
- Alzheimer’s disease – progressive (advancing) dementia, which involves brain atrophy (loss of brain mass) with the onset of loss of higher cognitive performance
- Postpartum depression (PPD; postpartum depression; unlike a short-lasting “baby blues,” this carries the risk for permanent depression)
- Premenstrual syndrome with dysphoric mood.
- Seasonal obsessive-compulsive disorder
The procedure
The patient is exposed to very bright white light. This light contains the complete spectrum except ultraviolet light, extreme blue components and some infrared components and is therefore harmless to the eye. The intensity of the illumination is between 2,500 and 10,000 lux. This is roughly equivalent to a sunny spring day and is 5-20 times more intense than average room lighting. The therapy device consists of approximately 6-8 40 watt fluorescent tubes. During the treatment the patient should sit at least 60-80 cm away from it. If possible, the light should be applied in the morning, as the greatest effectiveness has been proven here. The duration of therapy depends on the intensity of irradiation and is about 2 hours at 2,500 lux or about 30 minutes at 10,000 lux. During treatment, the patient can perform sedentary activities such as reading or eating, but should look directly into the light source every 30-60 seconds. With daily application, therapy success can be achieved after 3-4 days, while the overall effect depends on the dose or the length of application. Further notes
- A first small clinical study demonstrated that Bright Light therapy (1,350 lux; for 30 minutes every morning for 4 weeks; illuminating the face from about 45 cm away from the light box) can help cancer patients with general fatigue. The result of the study was striking. At the end of the study, no patient who had used the therapy suffered from fatigue anymore (versus 55% in the comparison group). Furthermore, sleep quality was improved; patients treated with Bright Light therapy had fewer waking periods during the night.
Benefit
Bright light therapy is a scientifically recognized form of light therapy that can be used effectively against depressive moods and can significantly increase the well-being of individual patients.
