For years, scientists have linked depression to mental, emotional, and psychological factors. They attributed depression to problems with family and friends, too much stress, certain medications and alcohol. However, a new study published in the American Journal of Epidemiology points to a different culprit: that tiny nighttime light in the bedroom. Besides turning off all lights in your bedroom, along with tablets and smartphones at night, what can you do to get your much-needed sleep?

Go under the sun — Sunlight helps maintain your circadian rhythm, the body’s built-in time-keeping clock and lengthens sleep duration. A study showed that insomniacs fell asleep 83 percent faster after they went under the sun. People whose work requires them to stay indoors throughout the day can invest in an artificial bright light device or bulb.

Take coffee during the day — Caffeine stimulates the nerves and can stop you from unwinding at night. In fact, one study revealed that drinking coffee six hours before going to bed worsens quality of sleep.

Sleep and wake up at the same time each day — Our circadian rhythm is dictated by the rising and setting of the sun. You can help the body unwind at night by mimicking this built-in system. This explains the results of a study that said those who slept at different times of the day and who stayed up late on weekends slept poorly. Other studies show that irregular sleeping hours changes the circadian rhythm and levels of melatonin, which tells your brain to go to sleep.