Burn the midnight oil too often, and you could be increasing your risk for depression and suicide.

Artificial light at night (LAN) is the problem. One study, which looked at the effect of nighttime light exposure on the elderly, found that the longer and more intense the exposure to light at night, the greater the chance of depressive symptoms.

“In our research so far, light exposure at night would be associated with depressive symptoms, sleep quality, metabolic abnormalities, and blood pressure, and a health problem like depression and insomnia are known to increase suicide,” explained study co-author and sleep researcher Kenji Obayashi, MD, PhD, a research lecturer at the Nara Medical University School of Medicine in Japan. The study was published in the Journal of Affective Disorders in 2013.

Researchers are still untangling the complicated ways in which lack of sleep, light at night, depression, and suicidality might be related. No studies have directly linked light at night to suicide, other than a 2009 study published in BMC Psychiatry that demonstrated a correlation between suicide, higher latitude, and summer months in Greenland.

Dr. Obayashi, however, said that light at night could be altering the body’s natural circadian rhythms, which relate to sleep/wake cycles and also seem to play a role in helping manage many of the body’s systems.

“Delayed circadian phase may cause depression and insomnia; however, this has not been yet established," he said. "In addition, LAN may alter human melatonin secretion pattern, which is the hormone associated with mental condition and sleep quality." Encouraging the continuation of research are studies such as one in Molecular Psychiatry in 2013 that pointed out that rates of major depression have increased just as humans have increasingly brightened the night.

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Some researchers have found that getting enough light at certain times of day can counter these effects, but Obayashi’s team found that light at night was related to depression regardless of people’s exposure to daytime light. Because circadian rhythms are a 24-hour process, not a single event, light throughout the day and night will affect them.

How to Dim the Lights

If you’re used to the chatter of television soothing you to sleep, it’s probably going to take time to adopt these mental health saving strategies. But try them anyway:

Switch off screens. Turn off television, laptops, phones, computers, and tablets at least an hour before bedtime. Try listening to the radio or an audiobook as you go through your bedtime routine.

Turn off television, laptops, phones, computers, and tablets at least an hour before bedtime. Try listening to the radio or an audiobook as you go through your bedtime routine. Use a red screen. If you can’t give up your tablet or phone, find an app that gives you a reddish nighttime screen to avoid the waking effect of blue light.

If you can’t give up your tablet or phone, find an app that gives you a reddish nighttime screen to avoid the waking effect of blue light. Dim the lights. As you go through your evening, cut down on the lights. For example, use lamps instead of overhead lights.

As you go through your evening, cut down on the lights. For example, use lamps instead of overhead lights. Keep your bedroom dark. “Use black-out curtains that prevent light from streetlights outside from entering the bedroom, and remember to turn off your bedroom television before falling asleep,” recommended sleep researcher Tracy Bedrosian, PhD, a postdoctoral fellow at the Salk Institute in La Jolla, Calif.

“Use black-out curtains that prevent light from streetlights outside from entering the bedroom, and remember to turn off your bedroom television before falling asleep,” recommended sleep researcher Tracy Bedrosian, PhD, a postdoctoral fellow at the Salk Institute in La Jolla, Calif. Wear a sleep mask. If you can’t completely control the amount of light in your room, cover your eyes when you go to sleep.

If you can’t completely control the amount of light in your room, cover your eyes when you go to sleep. Choose red nightlights. Light on the blue spectrum is most likely to affect your sleep, so skip clear bulbs or fluorescents. “Use low levels of light in the orange/red wavelength,” advised neuroscientist Randy Nelson, PhD, chairman of the department of neuroscience at Ohio State University in Columbus. Pick red light bulbs or use red goggles if you must move around at night.

Light on the blue spectrum is most likely to affect your sleep, so skip clear bulbs or fluorescents. “Use low levels of light in the orange/red wavelength,” advised neuroscientist Randy Nelson, PhD, chairman of the department of neuroscience at Ohio State University in Columbus. Pick red light bulbs or use red goggles if you must move around at night. Get bright early morning light. “I would very much like to get people exposed to broad spectrum light in the morning and cut down light at night,” emphasized Nelson. Get outside, if possible.

Many sources of artificial light have been around for a relatively short time, and research is just catching up to what that means for people's sleep/wake cycles. But you don’t have to wait for the final word to make mood-protecting dimmer choices at night.