Light therapy is a science-based treatment that is gaining increasing recognition for addressing psychological and sleep-related disorders. In this article, we dive deep into the workings, applications and scientific basis of light therapy.
What is the impact of light therapy on sleep?
Light therapy affects our biological clock through exposure to specially designed light sources. This artificial light, usually bright white-blue with an intensity of 9,000-10,000 lux, reduces the production of melatonin (the hormone that causes sleepiness) and stimulates serotonin (the happiness hormone). This process helps reset sleep-wake rhythms, which can lead to improvements in mood, energy and sleep quality. The light comes from light glasses or a lightbox that you can place on a table.
Light therapy works through connections between the retina in the eye and specific areas of the brain. Ordinary indoor lighting is not sufficient for this purpose: a standard table lamp provides only 300 lux, while office lighting is around 500 lux according to European standards (NBN-EN 12464-1). That is why specialized lamps or light-emitting glasses are used to achieve the desired therapeutic effect.
When is light therapy most effective?
One of the most well-known uses of light therapy is for seasonal affective disorder (SAD for short), also known as winter depression.
In northern Europe, about 30% of the population is affected by SAD annually. In Belgium and the Netherlands it is 8%, while 8% experience milder symptoms. This disorder is characterized by depressive symptoms such as fatigue, gloom and increased need for sleep during the dark winter months.
The cause lies in a lack of natural daylight, leading to a hormonal imbalance: less serotonin and more melatonin. Light therapy helps restore this balance and is considered a standard treatment for SAD. Many users report an improvement in their mood and energy levels within just a few days.
As you live closer to the equator, the chance of winter depression decreases. The closer to the poles, the greater the chance of SAD.
Even if you have been diagnosed with Delayed Sleep Phase Disorder (DSPD), or freely translated when your sleep phases have shifted, light therapy can provide relief. Night workers may also benefit from the use of light glasses or light bulbs.
| Morning person | Night Owl | |
| Challenge | Tired too early in the evening | Not being able to get out of bed in the morning |
| Light Therapy Moment | Afternoon or early evening | Immediately after waking up |
| Daylight Saving Time Tip | Adjust the time by about 15 minutes two days in advance. | Start the week before with about 10 minutes a day |
| Winter Time Tip | Extend the day; start 15 minutes a day in advance | Maintain a regular routine; stick to your bedtime |
Does light therapy help with other conditions?
Although light therapy is best known as a treatment for winter depression, research has shown that it can be effective for other conditions as well:
- Non-seasonal depression: Although the evidence here is more limited, light therapy is sometimes considered when medication is ineffective or has unwanted side effects.
- Bipolar disorder: Studies show that light therapy can help bipolar depression without increasing the risk of (hypo)mania. It is considered a third-line treatment option.
- Sleep disorders: Light therapy can help with problems such as shift work disorder, jet lag and delayed sleep phase syndrome. For night workers, smart light glasses are used to support circadian rhythms.
- ADHD-related sleep problems: In children with ADHD, sleep problems are often exacerbated by medication or behavioral symptoms. Research suggests that light therapy may help improve sleep quality and possibly even reduce ADHD symptoms.
- Dermatological disorders: Dermatologists have successfully applied light therapy as a treatment method for a variety of skin conditions such as psoriasis, eczema, vitiligo and uremic itchingfor several decades.
How do you use light glasses?
We would like to give you some practical tips for using light therapy when you experience a winter dip and too little daylight makes you dejected or when you have jet lag. These tips will also benefit elderly people who have more difficulty getting moving and therefore do not get outside often enough or people who work in a moderately lit work environment:
- Use light glasses or a lamp for 30 minutes immediately after waking up to activate your biological clock (if you’re a night owl) or in the late afternoon (if you’re a morning person).
- For activities later in the evening, for that day, additional use around 4 p.m. may be helpful.
- Possibly combine morning light with the use of orange glasses that block bright light in the evening to stimulate melatonin production in the evening.
In clinical settings, a structured protocol is usually followed, for example, 45 minutes of light therapy daily for one week, often in a psychiatric outpatient clinic.
If you have a delayed sleep phase disorder, always consult with your treating sleep specialist. But in that case, it’s quite possible that light-emitting glasses might be used in the evening to influence your sleep rhythm.
If you work alternating day and night shifts, know when it’s best to dim the lights or turn them up. Don’t wear light-blocking glasses in the morning if you want to go to sleep after a night shift. On the contrary, avoid bright light; wear sunglasses or orange-tinted glasses to block out bright light. When you need to stay alert and want to suppress melatonin production—such as while you’re working—you can use light-blocking glasses or a light therapy lamp. There are products on the market that connect to an app; this app guides you and tells you when it’s best to start light therapy and for how long.
Is light therapy healthy for everyone?
Let’s start at the beginning, because, as we mentioned earlier, the cause lies in the lack of natural daylight. You might also ask: Does everyone need light therapy with light-emitting glasses or extra lamps? No, they don’t! Just make sure to get plenty of daylight during the day—it doesn’t have to be sunny to get plenty of daylight. The best form of light therapy is to go outside more often during the day. And if that isn’t enough, you should definitely consider using additional aids.
Although light therapy is promising when applied correctly, there are some limitations:
- Evidence for non-seasonal depression and ADHD-related applications is still developing.
- Some conditions continue to require additional research to further substantiate effectiveness.
Still, light therapy certainly offers a safe option for many people. The number of side effects reported are rather low. As more studies are conducted, new uses may be discovered and protocols further refined.
Especially if you work alternating shifts or if your sleep is disturbed, you may want to consider light therapy. Light therapy is also a good strategy if you are a bit older, more difficult to walk and therefore somewhat deprived of daylight.
Conclusion – How does light therapy work?
Light therapy is a powerful method for treating mood disorders and sleep problems by resetting the body’s internal clock. Whether you’re struggling with seasonal affective disorder, sleep problems, or other related conditions, this therapy offers a scientifically proven solution that you can easily incorporate into your daily routine. With the right guidance, light therapy can help improve your mood, boost your energy, and promote healthier sleep habits.
