Slumber is significantly impacted by light. Morning light stimulates the body and mind, leading to emotions of alertness and vitality. In addition to stimulating awareness, light exposure at night can have a negative impact on a person’s ability to go asleep and stay asleep. Evening light exposure can make it more difficult to drift off to sleep. Frequent and long-lasting awakenings can occur if there is not enough darkness in the night.
How darkness influences sleep
To have a good night’s rest, you need to be in complete darkness. To the body, the absence of light is an important indication that it is time to sleep. At the wrong time of day, light exposure can disrupt both amount and quality of sleep by altering the body’s “sleep clock”—the biological process that governs sleep-wake cycles. For this reason, the pineal gland secretes melatonin, also known as “the sleep hormone” or the “darkness hormone.” Melatonin is a sleep-inducing hormone that tells the brain that it’s time to unwind. As the body prepares for sleep, muscles relax, tiredness sets in, and the body temperature decreases, this signal helps the body begin the process. At 3 a.m., melatonin levels are at their highest, a time when the body’s production of the sleep hormone is at its greatest. In the early morning, melatonin levels decrease and remain low for most of the day. Evening light exposure slows the body’s transition to sleep and the commencement of sleep itself because it interferes with the body’s natural melatonin rise.
Light as a modern sleep problem
We didn’t have to look for the dark for most of human history. Our connection with light and darkness was radically altered with the introduction of electricity in the 20th century. People are unaware of the negative effects of artificial light, which is affordable and ubiquitous, on their ability to fall asleep at night. Another potentially disruptive threat to sleep has been introduced by the ubiquitous use of digital technology and the light emitted from all those devices.
Measuring light: lux and lumen
It is important to know how light is measured so that you may better control your exposure to light and so improve your ability to fall asleep. These two metrics, lumen and lux, are critical in the field of illumination. The intensity or brightness of light at the light source itself is measured in lumens, which is also known as radiance. Light disperses and loses intensity as it goes away from its source. In other words, when it comes to our exposure to light, it isn’t just the intensity of the light that matters, but also our distance from the light. When it comes to that, we turn to our good friend lux. Lux takes lumen values and accounts for the amount of light that can be emitted from a given surface area. The brightness of a light bulb can be measured in lumens, but the brightness of the light in the room where it is located—and where you are—can be measured in lux. “Incident light” is another frequent term for lux measurements.
Using lux, indoors and out
These numbers can vary greatly based on both the source of the light, its power, and its closeness to the object being measured. Lux is a useful tool for measuring all sorts of light. As an example of lux, consider the following: 150,000 lux is a reasonable estimate for a sunny summer day. It’s not uncommon to see lux measurements as low as 1,000 on a cloudy winter’s day, when the sun is further away and veiled. As soon as the sun sets, the lux value plummets. A single lux of light from the moon generates all of the values.
Lux readings in a well-lit home, including lamplight and ceiling lighting, as well as light from the outdoors, can range from 300 to 500. The ease with which your body gets ready for sleep is influenced by the lux levels in your surroundings at night. Low illumination is essential in the nighttime hours, so that your body can naturally transition to sleep. In the evening, a lux level of less than 180 lux is recommended for activities such as reading before going to bed. At this brightness, you will be able to quietly go about your business without disturbing your body’s attempt to sleep. When the sun goes down, your bedroom should be pitch black, with little more than five lux.
Make light right for sleep
In order to ensure a good night’s sleep, you must control the amount of light that enters your home and your bedroom. In order to ensure that you have a good night’s sleep, it is important to pay attention to the details of your bedroom and arrange accordingly. Light from the outside world can disrupt your sleep if you don’t have curtains or shades in place. In order to keep out slivers of streetlight or early morning sunshine, make sure your window coverings are heavy enough and properly placed. Even a brief exposure to light can disrupt a person’s ability to fall asleep. The purpose of blackout curtains is to block out as much light as possible.
Nightlights can help
Use a nightlight with a red bulb if you require light in the night to get to the restroom or a child’s room comfortably. Compared to other light hues, red has a longer wavelength and is therefore less likely to disturb sleep. In a hallway or another room, try to place the nightlight so that it is not directly in front of you. To prevent needing to flood your nighttime environment with unpleasant, sleep-disrupting brightness, put a tiny light in position.
Ways to create darkness
In order to be ready for sleep, the body requires a certain amount of preparation time. Sleeping in a gradually darkening environment can aid in getting a good night’s rest. Reduce the brightness of the lights at least an hour before you want to retire for the night in order to help your body begin the process of preparing for sleep. Use a dimmer switch on overhead lights or low-watt, dimmable bulbs in lamps to manage the brightness. Turn off the TV, computers, and tablets, and put your phone away for the night an hour before you go to sleep. The blue light emitted by digital devices has been found in studies to be particularly harmful to sleep because of its high concentrations of this wavelength.
When worn at night, an eye mask can assist create a more ominous atmosphere while also shielding the eyes from bright light. You should look for a mask that is soft, comfy, and pliable. If you’re having trouble sleeping at night because of too much light, you may benefit greatly from wearing an eye mask.
As a result, you’ll pay more attention to the light that surrounds you, both during the daytime and at night. Creating a dark sleeping environment is a simple but critical step you may take to improve the quality of your sleep at night.
How Does Light Affect Sleep?
An individual’s circadian rhythm, the generation of melatonin, and sleep cycles are all impacted significantly by exposure to light.
How Does Light Affect Circadian Rhythm?
Several bodily functions, including sleep, are timed according to the 24-hour circadian rhythm. The circadian pacemaker, a small portion of the brain that is strongly influenced by light exposure, controls this pattern.
In the retina, a collection of cells detects light and carries it to the brain, where it is processed as a signal about the time of day1. After that, the brain transmits messages throughout the body2 to regulate organs and other systems in accordance with the current time.
It is possible for people to maintain their circadian rhythm by just being exposed to natural light, which causes them to be awake and sleepy at the same time that the sun rises and sets3. Despite the profusion of light sources in modern culture, the brain’s circadian pacemaker is disrupted.
The timing of light exposure affects how light affects the circadian rhythm. It is more difficult to fall asleep at night when the sun rises earlier in the day. The sleep cycle is pushed back by light exposure in the evening.
A person’s circadian rhythm is affected by the type of light and the length of time they are exposed to it. However, even a brief exposure to artificial light can have a significant impact on circadian rhythm4.
Circadian rhythms can become out of sync with the natural day-night cycle if exposed to too much or at the wrong time of day. As a result, they may experience sleep disturbances, weight gain, cardiovascular issues, and even an increased risk of developing cancer6.
Mental health and mood are intertwined with the circadian cycles of the body. A prevalent type of depression that affects persons who live in places with short winter days is seasonal affective disorder7. Circadian rhythms can be disrupted by the shorter days of winter, which can lead to seasonal mood swings.
How Does Light Affect Melatonin?
melatonin is a naturally occurring hormone that is strongly linked to light creation. If you are exposed to light for any length of time, your pineal gland will stop producing melatonin8.
One way melatonin aids sleep is through increasing drowsiness, which occurs as the hormone rises. In addition, melatonin’s daily synthesis cycles help maintain a regular sleep-wake cycle.
Sleeping difficulties, such as circadian rhythm disorders, may necessitate the use of synthetic melatonin, which is available as a dietary supplement.
How Does Light Affect Sleep Cycles?
A good night’s sleep isn’t the same as a bad one. There are four to six cycles9 in a typical night’s sleep, each lasting between 70 and 120 minutes. Multiple stages of sleep, such as rapid eye movement (REM) and non-REM sleep, make up these cycles.
Even a small amount of light exposure at night might impair the quality of sleep. Repeated awakenings can disrupt the sleep cycle and reduce the amount of time spent in deeper, more restorative sleep stages if there is too much light in the room.
How Does Light Affect Circadian Rhythm Disorders?
Sleep-wake disturbances of the circadian rhythm are caused by a malfunctioning or misaligned internal clock. A large number of circadian rhythm problems can be linked to light exposure patterns.
Long-distance plane travel can cause a condition known as jet lag. Because the body’s internal clock is still calibrated to the time zone of the leaving city, it frequently happens after traveling across five or more time zones11.
It’s possible for circadian rhythm to be disrupted by the incoming city’s distinct day/night cycle. Because of this, it’s possible that a person will have difficulty falling asleep, may wake up sooner than desired, or will have excessive daytime sleepiness.
In most cases, treating jet lag entails acclimating to the new time zone, such as by exposing yourself to daylight at specified times and avoiding light at other times in order to realign your circadian rhythm. This can take anywhere from a few days to a couple of weeks.
Shift Work Disorder
Shift job patterns necessitate working through the night or into the early morning hours. It is possible to work night shifts as part of a regular schedule or as part of a rotating one. More than a third of American workers have night or overnight shifts, according to the Bureau of Labor and Statistics.13
Shift workers are more likely to suffer from a disrupted circadian rhythm and the onset of shift work disorder since they must sleep throughout the day. As a result of a circadian rhythm disturbance, you may not get enough shut-eye or be more prone to workplace mishaps.
Other Circadian Sleep-Wake Disorders
Disorders in circadian rhythm can result from shifts in an individual’s internal clock that are either too far forward in the day or too far back in the night. The way a person lives and the amount of light they are exposed to are often the root causes of these issues.
Light therapy14 is a common treatment for many circadian diseases, which involves sitting near a high-powered lamp at specific times of day to retrain the body’s circadian rhythms.1 It is common practice to turn on the bright lighting in the morning to help keep the body’s internal clock in sync.
What Types of Light Affect Sleep?
There are some types of light that are more disruptive to sleep than others. When it comes to illuminance, daylight can reach 10,000 lux in direct sunlight, but even the brightest office lighting can only reach 500 lux at its brightest. Because of this, daylight has a significant impact on sleep and circadian rhythms.
When it comes to artificial lighting, there can be significant variances. More illuminance and brightness can be found in some varieties than in others. It’s worth noting, though, that even light that appears to be of the same brightness may actually have a different wavelength, which alters how it looks to the eye and brain.
As an example, LEDs emit blue light with a short wavelength. For melatonin and circadian rhythm, it is far more effective than light with a longer wavelength, according to research16. There is a link between excessive use of electronic devices, such as smartphones, tablets and laptops, and a lack of sleep.17
Is It Best to Sleep in Pitch Darkness?
In general, it’s preferable to sleep with the light off. Pitch-blackness minimizes the risk of sleep interruptions and disturbances.
Keeping a lamp on while you sleep disrupts your sleep patterns and causes you to wake up more frequently, which can be especially problematic in the hours leading up to your awakening.
Your eyelids cannot shield enough light by closing, according to scientific research20. Even while the eyes are closed, low levels of indoor light can have an impact on the circadian rhythm21.
In addition to improving the quality of your sleep, studies show that sleeping in complete darkness is preferable for a variety of other reasons:
- Eye strain: This can cause tightness, weariness, and discomfort in the eyes as well as greater trouble focusing if ambient light levels are too low during sleep.
- Weight gain: Circadian regulation of metabolism appears to be affected by keeping the lights on throughout sleep, even if sleep is not disrupted. Even after researchers took into account their eating and activity habits, women who slept with a light or TV on were far more likely to gain 10 pounds or more in one five-year study23.
- Cancer risk: At night, persons who live in homes with a lot of artificial light have a higher risk of developing breast and prostate cancer. After additional investigation, this correlation cannot be explained in terms of causation.
There are a slew of possible side effects to having too much artificial light in your bedroom, including disrupting your circadian rhythm, which plays an important role in encouraging many aspects of physical and mental well-being.
How Can You Adjust Your Bedroom Environment to Get the Best Sleep?
Make your bedroom as dark as possible as the first step in creating a sleep-inducing environment. To create a more ominous atmosphere, use blackout curtains to keep out as much light as possible.
Dim the lights as you get ready for bed. Low-power lamps can help ease the shift from daytime into night. There may be an association between low light intensity and sleep-inducing color temperature.25
Another thing you may do is get rid of or drastically minimize the amount of technology you use in your bedroom. The light from screens can disturb circadian rhythms, melatonin production, and sleep in general, hence they should be avoided whenever possible.
Electronic devices should be avoided in the bedroom if at all feasible to avoid the temptation of staying connected and receiving notifications. Avoid using electronic devices for an hour before bed and turn them off while you sleep if you cannot remove them from your bedroom entirely.
Tools that prevent blue light28 may be useful if you have devices in the bedroom. Special glasses can block blue light from penetrating your eyes, reducing the impact of blue light on your ability to sleep. Night mode on many smartphones and tablets can help limit blue light, but screen usage can still disrupt sleep patterns.
What About People Who Sleep With the Lights On?
Everyone isn’t a fan of sleeping in complete darkness. In this section, we’ll look at some of the likely causes of people sleeping with their lights on, as well as some strategies for combating the problem.
Having a light on as you sleep can either provide comfort or reassure those who are terrified of the dark.
These situations necessitate lower lighting levels. Even if you need a light to fall asleep, the majority of your sleep should be in complete darkness.
A mental health expert may be able to devise a plan to reduce anxiety before going to bed if you have severe phobias of the dark.
Lighting a Path to the Bathroom
When going to the bathroom at night, visibility is critical for many adults, especially the elderly who are more prone to falling.
To start, remove any carpets or cords that could provide a hazard to the floor. It is possible to use motion-activated lights in corridors or bathrooms to provide modest levels of light just when they are required.
Bed Partner Keeps a Light On
As a result, you can’t get a good night’s sleep if someone else keeps the TV or a light on.
If you and your partner can’t agree on how to keep the bedroom dark at night, you may be able to come up with a compromise. A lamp or a television should be kept at the lowest brightness setting if they insist on using them.
Wearing a snug-fitting eye mask may help if the light is still bothering you. Anecdotal research suggests that wearing an eye mask can help you get a better night’s rest30.
Falling Asleep With the TV On
If you fall asleep with the TV on, it will keep illuminating your room with artificial light until you wake up.
A simple solution is to get rid of the television in your bedroom. It’s possible your TV has a built-in sleep timer that will turn it off after a predetermined amount of time. Set a “lights out” time each night to turn off the television and utilize it to establish a consistent bedtime for your child.
Is There Ever a Time When Sleeping With the Lights on Is Better for You?
Even though it’s best to sleep in complete darkness, if you’re going to be napping during the day, some light may be helpful. Even if your naps are only 30 minutes long, keeping the lights on will help prevent you from drifting off into a deeper sleep than you intended.
What Other Steps Can Improve Sleep and Circadian Rhythm?
If you’ve been sleeping poorly for a long time and it’s affecting your energy, thinking, or mood, you should see a doctor to find out if you have a circadian rhythm disorder.
Your circadian rhythm and sleep hygiene are also important factors to consider. Healthy sleep can be supported by a variety of habits and routines, such as limiting caffeine intake, maintaining a regular sleep pattern, and engaging in regular physical activity.
How Does Light Affect Your Circadian Rhythm?
It’s hard to separate your circadian cycle from the effects of light. circadian is a Latin word meaning “around day,” and therefore the term was coined (2). Circadian rhythms follow a 24-hour internal clock that generally corresponds to the patterns of the sun, and these root words reflect that. Your brain receives a signal from your eyes when they detect light. Once your brain recognizes what time it is based on the strength of the perceived light, your internal biological systems are updated accordingly, including your energy levels and appetite.
This approach works best when the only light you are exposed to is natural. As the sun rises and sets, so do your feelings of alertness and sleepiness (4). Your eyes are constantly exposed to artificial light in today’s always-on environment, from fluorescent lights at work to the blue light from your smartphone.
How Does Artificial Lighting Affect Your Sleep?
It’s possible to interrupt your circadian rhythm when you’re exposed to artificial light for an extended period of time or when the light is exceptionally powerful.
As a result, many people find themselves fully awake at all hours of the night, fueled by hours of social media surfing or TV viewing. Even a few minutes of exposure to artificial light might disrupt a person’s sleep cycle. Chronic circadian rhythm abnormalities can cause a wide range of health issues, including obesity, mental health difficulties, and cancer (7). (7).
Even after you’ve drifted off to sleep, the quality of your sleep might still be impacted by artificial lights. Each night, your brain goes through a four-stage sleep cycle: light sleep, deep sleep, rapid eye movement (REM) sleep, and back again.
The transitions (8) between these sleep cycles can be disrupted if you are exposed to too much light at night. You’ll have worse quality sleep, and you’ll be more likely to wake up in the middle of the night, reducing the amount of time you get to spend in deep, rejuvenating sleep. You may wake up the next day feeling less rested, grumpier, and less focused than normal due to your lack of quality sleep the night before (9).
How Does Artificial Light Affect Melatonin Production?
Sleepiness is a common side effect of the hormone melatonin. In the evening, your melatonin levels rise and fall in accordance with your sleep-wake cycle, increasing to induce tiredness and decreasing to wake you up. Melatonin production is timed based on light cues received by the brain.
Sleepiness sets in earlier if you have a lot of light exposure in the morning. When you’re exposed to artificial light in the evening, when your brain normally needs to generate more melatonin, you have a problem.. Your brain thinks it’s still daytime, so melatonin production is inhibited, making you feel alert even if it’s your bedtime.
Are There Any Sleep Disorders Associated With Circadian Disruption?
Short-term and long-term sleep disturbances might result from a misaligned circadian cycle.
Having a circadian rhythm that is out of sync with your external environment might cause jet lag, which is what you feel (10). Air travel causes you to suddenly find yourself in a time zone where the sun’s patterns don’t match where you came from, which can be confusing. You may experience fatigue, sickness, and inability to sleep or wake up on time until your circadian rhythm gets used to the new surroundings.
Circadian misalignment can affect people who work night shifts or late hours because they have to be up and asleep at the same time. A circadian rhythm sleep-wake disturbance, shift work sleep disorder affects 10% of shift workers (11). Excessive drowsiness, decreased productivity, and an elevated risk of workplace accidents are all signs of this condition.
Seasonal affective disorder (SAD) is a type of seasonal sadness that affects some persons who live far from the equator (12). The symptoms of Seasonal Affective Disorder (SAD) include sleep disturbances, low energy levels, and food cravings that can lead to weight gain.
These conditions are frequently treated with light therapy. You can use a light box that mimics sunshine to perform this therapy at your own convenience. Individuals are required to sit in front of the box for a predetermined amount of time each day. There are two options for using the light box: either in the morning or at night, depending on how late they wish to sleep.
What Is Blue Light, and How Does It Affect Your Sleep?
All light has the potential to disrupt sleep, although some wavelengths have a greater influence than others. Study participants were exposed to blue or green light for 6.5 hours at night in one study, for instance (13). The generation of melatonin was delayed by two times with the blue light. When it comes to affecting your circadian cycle, blue light has the strongest effect.
As a result of the small wavelength of the blue light that is emitted by LED and electronic screens (15), your brain sees it as sunlight. Focus and mood are enhanced by blue light, which mimics the effects of natural sunlight. As a bonus, it keeps you alert. Melatonin production and sleep onset are delayed when your brain detects blue light.
This implies that if you spend your evenings staring at your phone, computer, or TV screen, you may be putting yourself at risk of a poor night’s sleep.
What Are Some Tips for Better Sleep?
There’s good news if you think artificial light is interfering with your sleep. To reduce your exposure and improve your sleep, only a few modest adjustments can go a long way.
Make Your Bedroom as Dark as Possible
It is better to sleep in a dark room. That’s all there is to it. Even with your eyes closed, the very act of having a light on might cause sleep disturbances. Getting up in the middle of the night or even sooner than you wanted to could be an issue.
Other areas of your health and well-being can be harmed by the lighting in your bedroom. In addition to disrupting your metabolism, sleeping with the lights on can cause eye strain (17). (18). Studies show that women who watch television or use lamps while they sleep are more likely to acquire weight or become obese.
To improve your night’s rest, use these strategies to darken your room:
- Sunlight and streetlights can be kept out of your room with the use of blackout curtains.
- To help you get a good night’s sleep, use dimmer lights in the hours leading up to bedtime.
- Remove all electronic devices from the bedroom, including your smartphone.
- Lock the screen and switch off notifications if you plan to have your phone with you at all times.
- Turn clocks and other electronic devices away from you.
- Use an eye mask to keep out extra light.
Choose a nightlight with a dim red bulb if you want one in your room. Your circadian clock is not affected by red wavelengths. A motion-activated one, on the other hand, is even better.
Monitor Your Light Exposure Throughout the Day
Taking care of your light exposure outside of your bedroom will help you get a good night’s sleep and stay awake during the day. Try the following:.
- Reduce the amount of time you spend in front of bright lights at night. When it’s time to go to sleep, dim the lights or utilize warmer bulbs to tell your brain it’s time to do so.
- At least an hour before going to sleep, limit your usage of electronic devices and avoid using them for at least a few hours.
- In the evening, activate night mode on your phone and tablet.
- When using a computer or a smartphone, consider donning blue light-blocking eyewear. These can reduce the effects of sleeplessness by blocking out some of the blue light.
Let in as much natural sunshine as possible during the day. A boost in mood and energy, and a realignment of your circadian cycle, will result from this. Circadian rhythms can be advanced by 30 minutes for every hour spent outside, according to studies.