How to Use Light Therapy for Sleep?

Light Therapy Explained

Light therapy’s beginnings can be traced back to ancient Egypt, India, and Greece. At that time, they practiced various forms of heliotherapy^[1] (“sun therapy”) in which patients had their whole body exposed to the sun to treat various mental and physical ailments.

Cut to several millennia later, and light therapy is still being used to treat various mental and physical ailments including:

• Insomnia
• Circadian rhythm sleep disorder
• Seasonal affective disorder (SAD)
• Jet lag
• Shift work
• Depression
• Alzheimer’s or dementia

These days, though, we have advanced technologically well beyond just lying in the sun, and light therapy is generally done with a special light box or visor^[2]. Patients will sit in front of this light for a set amount of time at various times throughout the day.

The light boxes should have a light intensity of about 10,000 lux^[3] to be effective, and they are designed to mimic natural sunlight but without the harmful UV rays. To put that into perspective, this is about 100 times4 brighter than normal indoor lighting, and a bright, sunny day is about 50,000 lux or more. Light boxes with this intensity can be used for just 20 to 40 minutes per session, but boxes with weaker light will need to be used for longer.

Light Therapy for Mental Health

Light therapy is considered a well-known method for treating various mental health issues, including:

• Depression
• Perinatal depression
• Seasonal affective disorder (SAD)
• Alzheimer’s and dementia^[5]
• Bipolar disorder^[6]

During a light therapy session, your eyes’ retinal cells will receive the light from the light therapy box, which affects the levels of both melatonin and serotonin^[7] in your brain. Serotonin^[8] is the precursor for melatonin, the hormone that regulates sleep, and serotonin also plays a key role in mood.

Low levels of serotonin have historically been associated with many mental health conditions including depression, anxiety, sleep problems, digestive issues (as serotonin is located in the gut), panic disorders, schizophrenia, and more^[8]. Though new science^[9] has recently come out questioning the link between serotonin and depression, it is still clear that serotonin plays an important role in mental health and sleep.

Plus, not feeling good mentally can impact your ability to sleep well, which in turn, will impact your mental health. This cycle of poor mental health and sleep is well documented^[10].

Studies show that light therapy can be an effective^[11] way to improve mental health and thus improve sleep.

Light Therapy for Sleep

Even if mental health is not a factor for you, light therapy can help treat several sleep issues, including:

• Insomnia
• Circadian rhythm sleep disorders
• Jet lag
• Shift work sleep disorder

Light plays an important role in regulating your body’s circadian rhythm. This is a big concept, but in the simplest of terms, our bodies operate in 24-hour cycles of sleeping and waking^[12]. Light tells the body that it’s time to be awake, and darkness tells the body that it’s time to start producing melatonin and getting sleepy.

However, this gets more complicated when people are in circumstances that disrupt this biological clock, such as jet lag from travel, shift-work jobs, circadian rhythm disorders, and insomnia.

Light delays the release of the hormone melatonin, which is important for fostering sleepiness. Therefore, light therapy can be utilized to get your internal clock back on track.

In scientific terms, it works by stimulating cells in the retina that connect to the hypothalamus, the part of the brain that helps control your body’s circadian rhythms^[4]. When you activate the hypothalamus at certain times of the day, it can help restore a normal circadian rhythm, which is good news for those who have trouble sleeping.

Light Therapy for Insomnia

Insomnia is the inability to fall or stay asleep, and it can be short-term, lasting for only a few days or a few weeks, or long-term for months at a time. People can experience insomnia for a variety of reasons, such as depression or anxiety, stress, a change in schedule, or a new environment.

A 2016 systematic review^[13] of over 50 studies showed that light therapy can be an effective tool for treating insomnia. Furthermore, it seemed to be especially effective at a higher intensity, for insomnia in female participants, and for those who struggled with insomnia due to Alzheimer’s disease or dementia.

Light Therapy for Circadian Rhythm Sleep Disorders

This same 2016 review found that light therapy was an effective treatment for circadian rhythm disorders13.

Circadian rhythm disorders^[14] are problems that occur when your body’s internal clock, which tells you when it’s time to sleep or wake, is out of sync with your surrounding environment. For example, you might wake up way too early each morning or feel tired way too late at night.

Since light^[15] is the best tool for training your circadian rhythm, or getting it back on track with your environment, these boxes that emit light could be an effective solution for circadian rhythm disorders.

Light therapy will be recommended at different times of the day, depending on what you are struggling with. If you are getting tired too early in the evening, for example, you might be instructed to use the light box in the afternoon. If you are not getting tired until late in the night (or early morning hours), you’ll be instructed to use the light box first thing in the morning.

You’ll need to talk to a doctor to figure out when and how to best use light therapy for circadian rhythm disorders.

Light Therapy for Jet Lag

Jet lag happens when you travel across time zones, but your circadian rhythm remains synchronized with your normal location. For example, if you fly from New York to Paris, there will be a six-hour time difference in time zones. This means that by 10:00 p.m. in Paris, you’ll only feel as tired as if it were 4:00 p.m., and you might only start to feel sleepy around 4:00 a.m. in Paris, which would be 10:00 p.m. back home in New York.

In short, your circadian rhythm will be out of sync with the light and dark cycles of your new environment. Therefore, getting outside in the sunshine in the morning and late afternoon/early evening can help with jet lag by teaching your body when it is morning (time to be awake) and dusk (time to get sleepy). However, research shows that light therapy can help accelerate this process^[16].

Light Therapy for Shift Work Sleep Disorder

Shift workers are people who have to work late into the night or wake up and start their day very, very early. Many people in the medical field, for example, have to work all night. This schedule disrupts an otherwise normal circadian rhythm, which often results in insomnia or excessive daytime sleepiness.

Research^[17] shows that light therapy can help shift workers feel more alert during the night when they need to be awake. Since shift workers typically sleep during daylight hours, they also need to adjust their bedroom environment for their schedule. Investing in blackout curtains, for example, can help keep light out to foster sleepiness.

Light Therapy at Home

The good news is that light therapy is easy and accessible, with different devices available. Rather than looking directly into the light, you position your face about 16-24 inches away from the light3. This means you can do light therapy at home while you are doing other tasks like working, reading, or talking on the phone.

The most common at-home light therapy devices include:

• Desk lamps
• Floor lamps
• Alarm clocks
• Wearable visors

Generally, you should look for a light device^[18] that produces 10,000 lux of either cool-white fluorescent light or full-spectrum fluorescent light and has the smallest amount of UV possible (none would be best.)

According to the University of British Columbia^[19], you should start your sessions with just 30 minutes per day. If you are using this for issues getting to sleep at night or any form of depression, do this early in the morning and as soon as possible after waking.

You’ll usually position the light device 16-24 inches from your face, but see the manufacturer’s guidelines about appropriate distance. The University of British Columbia also advises never looking directly into the light.

You can buy a light box without a prescription, but because light therapy affects your mood and circadian rhythm, and may come with additional side effects, we recommend consulting a doctor before using one.

Side effects^[20] of light therapy can include eye strain, jumpiness/jitteriness, headache, nausea, skin itchiness or irritation, and poor vision. People with bipolar disorder^[21] are more likely to experience side effects, as well as people with certain eye or skin conditions that make them more sensitive to sunlight.