Light therapy lamps are often recommended for those suffering from seasonal affective disorder during the dark days of winter. But can they help address sleep issues all year round? And how do they work?
How light therapy can help sleep
Our circadian rhythm (in effect, our 24-hour body clock) is strongly influenced by exposure to daylight and darkness. Generally speaking, exposure to light tells the body that it’s time to be awake while exposure to darkness tells the body to prepare for sleep. This influence is one of the reasons why backlit electronic devices can be so disruptive to sleep.
Individuals who are suffering from a circadian rhythm sleep disorder will not follow the expected cycle of falling asleep at around 11:00 p.m. and waking at around 7:00 a.m. Instead, they may go to bed early at night and wake early in the morning, or go to bed late at night and wake late in the morning. Other individuals may not follow a recognized sleep pattern, taking numerous naps instead of having one long sleep.
When the circadian rhythm is out of sync in this way, exposure to bright light may help.
Who benefits most from light therapy lamps?
In addition to helping those with a circadian rhythm sleep disorder, bright light therapy may also help those with insomnia — particularly sleep onset insomnia (difficulty falling asleep).
One study found that those who suffered from sleep onset insomnia fell asleep faster, earlier in the evening, and slept for longer than a control group after sitting in front of a light therapy box for one hour over a seven-day period.
Those in the bright light group also reported:
- Reduced insomnia severity
- Less pre-sleep anxiety
- Less daytime fatigue
- Improved daytime functioning
A separate study found that exposure to 45 minutes of bright light every morning for 60 days helped individuals fall asleep faster, increased total sleep duration, and reduced daytime fatigue.
How (and when) to use a light therapy lamp
The intensity of light emitted by light therapy lamps is measured in lux.
If you tend to fall asleep late at night, exposure to 10,000 lux of light for at least 30 minutes as soon as you wake may help advance the body clock, helping you fall asleep the next night at an earlier hour.
If you tend to fall asleep very early in the evening and struggle to stay asleep past around 4:00 a.m., try following the same routine as above but expose yourself to the light between two and four hours before you would normally go to bed. This may help delay the body clock, helping you stay awake until a later hour.
Features to look for in a light therapy lamp
Look for a light therapy lamp that emits at least 10,000 lux, but keep in mind that lux varies according to how close you are to the light source. For example, one lamp may emit 10,000 lux at 14 inches while another may emit 10,000 lux at 12 inches. Find out the technical specifications of the lamp you’re interested in to make sure it is appropriate for you.
You do not need to spend extra on a light therapy lamp that emits full spectrum light but you should aim to buy a lamp that emits as little ultraviolet (UV) light as possible.
Finally, look for a lamp with a built-in timer if you aren’t good at keeping track of time.
If you’re still confused by all the available options, ask your doctor for advice. It is especially important to seek medical advice before using a light therapy box if you have past or current eye problems.