Main Research Findings

Bright light therapy has been established for treatment of winter depression, or seasonal affective disorder (SAD). This therapy is effective in treating winter depression. Analysis of side effects most often have focused on a narrow set of suspected symptoms, based on clinical observation (e.g. headache, eyestrain, nausea, insomnia, and hyperactivity). This study broadens the purview to a set of 88 physical and subjective symptoms that might emerge, remit, or remain unchanged relative to baseline, thus reducing bias toward assessment of presumed side effects.

Another study conducted a double-blind random-ordered comparison of the effects of placebo and 5-hydroxytryptophan (200 mg, orally) in ten depressed patients with seasonal affective disorder (SAD) and ten controls. Results showed slightly but significantly higher basal levels of serum prolactin and a trend toward higher basal levels of serum cortisol in the patients with SAD compared with controls. After administration of 5-HTP, the cortisol level significantly increased and the prolactin level significantly decreased in both patients and controls. No differences in the melatonin level, growth hormone level, blood pressure, or pulse rate and no side effects were noted between patients and controls in the two study conditions; the timing of basal and 5-hydroxytryptophan-stimulated hormonal secretions was similar for both groups. 1

Bright light treatment has become an accepted treatment for seasonal affective disorder (SAD), but there have been few studies about adverse effects from using this treatment. 2 We conducted a study to examine the frequency of adverse effects of bright light treatment for SAD. 2

Reasons for Side Effects

Side effects of bright light therapy can be caused by excessive exposure to light. Light can affect the secretion of melatonin, which regulates the body's internal clock. 1 Changes in melatonin secretion can affect sleep and mood. 1

Common Side Effects

Headache

Headache is a common side effect of bright light therapy.

Eyestrain

Eyestrain is another common side effect of bright light therapy.

Nausea

Nausea has been reported as a side effect of bright light therapy.

Insomnia

Bright light therapy can affect sleep patterns and may cause insomnia.

Hyperactivity

Bright light therapy can cause hyperactivity in some people.

Side Effects Management

Headache

To reduce headache, you can try increasing the distance from the light source, reducing the intensity of the light, or taking breaks.

Eyestrain

To reduce eyestrain, you can rest your eyes or use eye drops.

Nausea

To reduce nausea, you can try increasing the distance from the light source, reducing the intensity of the light. You can also take medication to prevent nausea.

Insomnia

To prevent insomnia, it is important to avoid bright light therapy before bed.

Hyperactivity

To reduce hyperactivity, you can try reducing the intensity of the light or increasing the distance from the light source.

Comparison of Studies

Similarities

All three studies suggest that bright light therapy is effective in treating SAD. 1 2 They also suggest that bright light therapy can cause side effects. 2

Differences

The three studies differ in the symptoms investigated and the methods used to assess side effects. 1 2 investigated a comprehensive set of 88 physical and subjective symptoms, while 1 measured hormone levels, such as serum prolactin, serum cortisol, melatonin, growth hormone, blood pressure, and pulse rate. 2 examined the frequency of adverse effects of bright light treatment for SAD. 2

Points to Consider for Everyday Life

Bright light therapy can be effective in treating SAD, but it is important to remember that there is a risk of side effects. 2 It is recommended that you consult with your doctor before starting bright light therapy and discuss ways to minimize side effects. 2

Limitations of Current Research

Research on the side effects of bright light therapy is limited. 2 More research is needed. 2

Future Directions for Research

Further research is needed on the side effects of bright light therapy. 2 It is necessary to investigate the frequency and severity of side effects. 2 It is also necessary to investigate methods to minimize side effects. 2

Conclusion

Bright light therapy is effective in treating SAD, but it can cause side effects such as headache, eyestrain, nausea, insomnia, and hyperactivity. 2 It is recommended that you consult with your doctor before starting bright light therapy and discuss ways to minimize side effects. 2