Light is one of the most critical factors that helps to regulate your sleep and wake cycles. But it’s not just sunlight isn’t the only kind of light that affects sleep — a recent study shows how the lighting in your home, and even the choice of lightbulbs you use can also interfere with your body’s ability to wind down for the night.
Your circadian rhythms, or internal body clock, help control your natural sleep-wake cycle. These rhythms have been shown to be incredibly sensitive to any kind of light, whether that be natural (solar) or artificial lighting. When and how you expose yourself to light has a big impact on your circadian rhythm and the biological clocks that control many bodily functions, like digestion, hormone regulation and body temperature.
Light blocks the production of melatonin, which helps you fall asleep, so exposure to light before bed can impact your ability to fall asleep as well as your overall sleep quality. In fact, spending time in a fully lit room before trying to go to sleep can cause your body to delay and shorten melatonin production compared to spending time in a dimly lit room before trying to sleep.
Darkness is essential to sleep. The absence of light sends a critical signal to the body that it is time to rest. Light exposure at the wrong times alters the body's internal "sleep clock"—the biological mechanism that regulates sleep-wake cycles—in ways that interfere with both the quantity and quality of sleep. Melatonin, a hormone produced in the brain's pineal glad, is often known as the "sleep hormone" or the "darkness hormone." Melatonin influences sleep by sending a signal to the brain that it is time for rest.
This signal helps initiate the body's physiological preparations for sleep—muscles begin to relax, feelings of drowsiness increase, body temperature drops. Melatonin levels naturally rise during the early evening as darkness falls and continue to climb throughout most of the night, before peaking at approximately 3 a.m. Levels of melatonin then fall during the early morning and remain low during much of the day.Evening light exposure inhibits the naturally timed rise of melatonin, which delays the onset of the body's transition to sleep and sleep itself.
If you need a source of light during the night—to make your way comfortably to the bathroom or to a child's bedroom—use a nightlight with a red bulb. Red is a long wavelength light that has been shown less disruptive to sleep than other light wavelengths. Put the nightlight in a hallway or another room, if possible. Having a small light in place will help you avoid having to flood your middle-of-night environment with unwanted, sleep-disrupting brightness.
The body needs time to prepare for sleep. A sleep routine that includes a gradually darkening environment can help. Dim the lights a full hour before bedtime to encourage your body to begin its physiological progression toward sleep. Use a dimmer switch on overhead lights to control their brightness, or install low-watt, dimmable bulbs in lamps. Avoid screen time the hour before bed: turn off the television, power down computers and tablets, and put your phone away for the night. The light from digital devices contains high concentrations of blue light, a wavelength of light that research has shown is especially detrimental to sleep.
An eye mask worn at night can help deepen darkness and protect against intrusive light. Choose a mask that is soft, comfortable, and flexible. Wearing an eye mask can take a little getting used to, but it is a highly effective tool for limiting your light exposure at night.