Major Research Findings

Two studies investigated the side effects of bright light therapy (LT). The first study broadened the scope of side effect analysis from a narrow set of suspected symptoms (e.g. headache, eyestrain, nausea, insomnia, and hyperactivity) to a comprehensive set of 88 physical and subjective symptoms, reducing bias towards presumed side effects. The second study 1 examined the acute side effects of a single 30-minute session of bright white light (10,000 lux) versus dim red light (<500 lux) in a randomized sample of healthy young adults. This study found no significant difference in the incidence of any reported side effect between the LT group and the placebo group. However, both groups showed small but statistically significant increases in eye strain and blurred vision.

Reasons for Side Effects

The exact reasons for side effects from bright light therapy are not fully understood. However, factors such as light intensity, exposure duration, and individual sensitivity are believed to play a role.

Common Side Effects

Headache

Headaches can occur as a side effect of LT. , 1

Eye Strain

LT can cause eye strain and blurred vision. 1

Nausea

Nausea can occur as a side effect of LT.

Insomnia

LT can cause insomnia.

Hyperactivity

Hyperactivity can occur as a side effect of LT.

Managing Side Effects

Headache

If a headache occurs, increasing the distance from the light source, reducing the intensity of the light, or taking a break can be effective. Over-the-counter pain relievers may also be helpful.

Eye Strain

If eye strain occurs, taking regular breaks, closing the eyes and resting them, and eye stretches can be helpful. Using eye drops can also be beneficial. 1

Nausea

If nausea occurs, increasing the distance from the light source or reducing the intensity of the light can be effective. Staying hydrated and consuming light meals can also be helpful.

Insomnia

If insomnia occurs, shifting the LT time to daytime or reducing the intensity of the light can be effective. Incorporating relaxing activities before bedtime can also be helpful.

Hyperactivity

If hyperactivity occurs, reducing the duration of LT or the intensity of the light can be effective. Incorporating relaxing activities can also be helpful.

Comparison of Studies

Similarities

Both studies investigated side effects of LT and mentioned common side effects such as headache and eye strain. Both suggest that the occurrence of side effects varies depending on individual sensitivity and LT conditions.

Differences

The first study investigated a broader range of potential side effects for LT used in SAD treatment, while the second study 1 focused on acute side effects in healthy young adults. Therefore, the second study did not mention long-term side effects of LT.

Implications for Real-Life Application

LT is an effective treatment for seasonal affective disorder and regulating the body clock. However, it's essential to remember the risk of side effects. Before starting LT, it's crucial to consult with a doctor or specialist to determine the most suitable approach for your individual needs. It's also important to be aware of any changes in your health during LT and discontinue it immediately if necessary.

Limitations of Current Research

Research on side effects of LT is still insufficient, and long-term side effects remain largely unknown. Further investigation is needed to understand how age, health conditions, and lifestyle factors may influence side effects.

Future Research Directions

Further research on long-term side effects and the impact of various factors on side effects is necessary. Developing effective strategies to mitigate side effects is also crucial.

Conclusion

LT is an effective treatment for seasonal affective disorder and regulating the body clock, but it's essential to be aware of the potential for side effects. Consulting with a doctor or specialist before starting LT and being attentive to any changes in your health during LT are crucial steps. There are still many unknowns regarding side effects, and further research is needed.