How artificial light affects our sleep patterns
By Dan LaVine | 07.31.2019
How artificial light affects our sleep patterns:
Whether neon numbers glare from your nightstand alarm clock, your iPhone lights up when receiving a message, or the television screen glows bright on your bedroom dresser, artificial light is all around us. While it may help us be more productive during the day, all of this artificial light comes with a cost, especially when it comes to sleep.
The Effects of Artificial Light
As lamps and indoor lights have allowed you to remain awake long past sunset, they've also caused you to move farther and farther away from natural sleep patterns. People who lived during the Industrial Age, before artificial lights, slept very differently from the way we sleep today. Many snoozed in two four-hour shifts, separated by a late-night period of being quietly awake. When artificial light is taken away, humans tend to revert back to this natural, two-shift sleep pattern.
Artificial light disrupts the body's circadian rhythm—the body’s 24-hour sleep/wake cycle—and has been shown to affect things like brain wave patterns, hormone production, and cell regulation. Disrupting this circadian rhythm has also been linked to medical issues like depression, obesity, breast and prostate cancer, and cardiovascular disease. It's even associated with sleep disorders like insomnia and, possibly because it causes the suppression of melatonin, a sleep-inducing hormone.
Have you ever woken up just minutes before your alarm goes off and marveled at your body's sense of time? Humans (and most living creatures) have an internal clock that mirrors nature's cycles of day and night.
Nestled deep in an area of the brain called the hypothalamus, this timekeeper regulates many of our body's functions, such as sleep, energy, and hunger.
Sunlight detected by cells in the retina of the eye sends messages to the brain that keep us in a roughly 24-hour pattern. These light cues trigger all kinds of chemical events in the body, causing changes in our physiology and behavior. For example, as evening approaches and the light in our environment dwindles, the hormone melatonin begins to rise and body temperature falls—both of which help us to become less alert and more likely to welcome sleep. With the help of morning light, melatonin levels are low, body temperature begins to rise, and other chemical shifts, such as an uptick in the activating hormone cortisol, occur to help us feel alert and ready for the day.
Fixing the Problem
A few small changes can help minimize the problems associated with sleep and artificial light. For starters, don’t keep your phone near you when you sleep, and avoid all artificially lit screens (like televisions, iPads, and iPhones) right before bedtime. Shield artificial light properly in the bedroom (by turning your alarm so that the light faces away from you, for example), and use light at night only when it’s absolutely needed.
How darkness influences 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.
Make light right for sleep
Managing your exposure to light in your home and in your bedroom is fundamental to creating a healthy sleep environment. With awareness, attention, and some simple planning, you can create a bedroom that guards against unwanted light at night, and protects the quality of your sleep until you are ready to wake. Curtains and shades on windows keep outside light from disturbing your sleep. Make sure window coverings are heavy enough to fully block light, and are well fitted to avoid slivers of streetlight or early morning sunlight from filtering in. Even brief exposure to light can interfere with sleep. Blackout curtains are designed to provide this kind of thorough protection against unwanted light.
Nightlights can help
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.
Ways to create darkness
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.
Being aware of light's effects on the body will lead you to pay more attention to the light that surrounds you, both day and night. Taking a little time to ensure a dark sleeping environment is one easy and important way to protect and improve your nightly rest.