Many of us have trouble sleeping and experience times during the day when our energy or mood lags. This can be more pronounced in the fall and winter when the days are shorter and darker.

The good news is that you don’t have to turn to medication to fix these problems. The way to restful sleep, increased energy and a better mood may be as easy as exposing yourself to the right amount of light at the right time of day. Here’s how to do it…


Many of us spend most of our days indoors. Even if our homes or offices seem to get a lot of natural light through windows, a light meter held in the room would show that the amount of light indoors registers much lower than just outside the window. In the evening, when our inner clock needs to wind down, we are inundated by artificial light from lamps, computer monitors and television screens. In our bedrooms at night, a night-light, streetlights, bathroom light, etc., can disturb sleep timing and quality.


By changing the amount and patterns of your daily light exposure, remarkable changes in your mood, energy and sleep can occur within days.

EXTRA: For 28 more articles with a wide variety of information on helping you sleep, go to Bottom Line’s Guide to Better Sleep…No Sleeping Pills Needed.

What to do: Buy a fluorescent light box that provides 10,000 lux of illumination (lux measures the light level reaching your eyes from the source). That is the equivalent of the amount of light that you would get while walking on the beach on a clear morning about 40 minutes after sunrise. The lamp should have a screen that filters out ultraviolet (UV) rays, which can be harmful to the eyes and skin. It should give off only white light, not colored light, which has been hyped to be especially potent but is visually disturbing and no better than white. To be sure of a big enough field of illumination, the screen area should be about 180 square inches (for example, 12 inches x 15 inches) or larger.

A good brand that meets all of the requirements is the BOXelite OS by Northern Light Technologies, which costs about $180, including a lux meter, from the nonprofit Center for Environmental Therapeutics (CET). Many insurance companies will fully or partially cover the cost of a light box if you provide a physician’s letter. Adjust the light box so that the light comes from above your line of sight and you feel comfortable and are not squinting. The lux meter is used to verify the 10,000 lux level at your sitting position about 14 inches from the screen. You can get the benefits of the light while talking on the phone, using your computer or enjoying breakfast. You sit facing forward, focused on the work surface, while the light shines down at your head from in front.

While side effects from light therapy are rare and relatively minor, they can occur. If you experience eyestrain, headache, queasiness or agitation after beginning light therapy, reduce the light dose by sitting farther away from the light box or shorten the duration of exposure.


When do you prefer to go to sleep, and when do you like to wake up? Your answer indicates your chronotype, your individual inner clock. To determine your chronotype, take CET’s chronotherapy quiz. The results will tell you the amount and timing of light therapy that will work best for you, but here are general recommendations….

You fall asleep too early. You find it hard to stay awake at night and typically wake up very early in the morning.

Prescription for light therapy: Use a bright-light therapy box for 15 to 30 minutes about an hour before you typically get sleepy.

Other helpful strategies for staying awake and pushing your sleep cycle forward…

Make lunch your major meal of the day, then eat only a light dinner.

Avoid napping, especially in the afternoon and evening. Instead, distract yourself from your fatigue by moving around and doing stretches.

Turn up room lights during the evening.

You fall asleep too late: You try to get to bed at a decent hour but can’t fall asleep. Then you have trouble waking up for work or school.

Prescription for light therapy: Use a light box for 15 to 30 minutes within 10 minutes after your natural wake-up time. If this time is later than your work schedule allows, begin light therapy on a long weekend. Then begin shifting your wake-up time and light-therapy schedule earlier—in 15-minute steps—as soon as you feel comfortable waking up at the new time.

More strategies for shifting your inner clock earlier include…

Finish dinner at least three hours before bedtime. Avoid alcohol after dinner.

Minimize napping, especially in the second half of the day. Try to get outdoors, keep moving and do some stretches instead.

Avoid bright blue-light exposure in the evening. Use the free programmable “f.lux” blue-light blocker on your computer screen. The blue light in screen displays can inhibit sleep onset hours later. If you are working or studying at a library in the evening, wear a pair of blue-light-blocking glasses, such as LowBlueLights protective glasses or “fitovers.”

Keep your bedroom dark until you wake up. Early morning light seeping in through the windows actually can worsen a late-sleep pattern.

You sleep fitfully. Prescription for light therapy: Take light therapy—or spend time in the sun—in the middle of the day. Enhancing midday light exposure often improves sleep quality at night.

Other strategies to help you sleep through the night include…

Do not drink alcohol after dinner.

Keep your bedroom dark.

If you tend to wake up at night to use the bathroom, install amber-colored night-lights in the bathroom and hallway instead of turning on bright lights, which can disrupt your sleep.

You are unable to fall back to sleep after waking in the middle of the night. There could be many causes for this type of sleep problem, such as anxiety, depression and physical illness, so it is best to consult a doctor. However, using light therapy in the evening to push sleep onset later (see “fall asleep too early”) may help some people sleep through the night.


You can use bright-light therapy at any time during the day to increase your energy and alertness. Some people can quickly recharge with a brief session of light therapy (as little as 10 minutes) when they first feel an energy slump.

Caution: See a doctor if you are chronically lethargic—this can be a sign of depression, a medical sleep disorder (such as apnea) or other illness.

If you’re feeling sad or mildly depressed, the light-therapy regimen is the same as the prescription for falling asleep too late, though you may need to test morning light sessions longer than 30 minutes (up to an hour) to feel a strong enough effect.

Caution: It can be difficult for an individual to know the difference between mild depression and moderate or severe depression. If you are suffering from moderate or severe depression, a physician will need to monitor your progress with light therapy and consider other treatment options. To help determine where you fall on the depression spectrum, take CET’s confidential self-assessment. You can print out the results to bring to your doctor.