Does Light Affect Your Ability to Sleep?

Did you know that light is the most important external factor influencing your sleep? Natural light helps regulate our internal clock to make sure we are fully awake during the day and sound asleep at night. Artificial light exposure, especially at night, can confuse our biological clock and cause sleeping issues. 

This article will help you understand the crucial role light plays in regulating our sleep. It will also explain how different types of light can affect our sleep-wake cycle differently. Finally, we will discuss tips and tricks to minimize the negative influence of light on your sleep.

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What Are Circadian Rhythms? 

Circadian rhythms are 24-hour cycles that act as an internal clock. They are responsible for regulating many functions within our bodies, including sleep. They are controlled by a small brain region called the hypothalamus, or the circadian pacemaker.

Light is one of the biggest influences on our circadian rhythms. When light enters the eye and hits the retina, it sends a message to the brain regarding what time it is. The brain then interprets this information and sends messages back throughout the body to regulate activity based on the time of the day. For example, if the brain senses it is morning, it will activate the intestines to stimulate movement. In other words, it prepares your body for digestion as you are nearing breakfast time.

The sleep-wake cycle is another function controlled by the circadian rhythm. As mentioned above, natural light strongly influences the circadian rhythm, enabling a person to stay awake during the day and fall asleep at night. When it is light out, your brain receives strong light signals. In response to this, it sends impulses throughout your body to promote alertness. As the light goes down, the body starts producing a hormone called melatonin. The person then becomes drowsy and gets ready for bed. Melatonin also promotes good sleep quality

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What Are Circadian Rhythm Sleep-Wake Disorders? 

Circadian rhythm sleep-wake disorders (CRSWD) include having trouble falling asleep, waking up frequently throughout the night, waking up too early, and being unable to go back to sleep. Some of the reasons someone might suffer from a CRSWD include exposure to excessive artificial light at night and shift work. 

Humans are now more and more exposed to artificial light, especially at night when the body is supposed to go into sleep mode. Artificial light can delay the natural sleep-wake cycle, making it harder to fall asleep at night. Lights from smartphones or other types of screens can also have this effect. For example, a study found that reading an e-book for a few hours at night was sufficient to reduce evening sleepiness, decrease melatonin secretion, and delay sleep onset. 

Shift work can also seriously damage someone's internal clock. Unfortunately, some individuals, like nurses, bartenders, firefighters, security guards, blue-collar workers, and doctors, have no choice but to take a night shift. Some of them even work nights exclusively. In fact, The Bureau of Labor and Statistics estimates that around 16% of workers in the United States have to work evening or night shifts. These people have to be active during the night and sleep during the day, which is basically opposite to what the circadian rhythm is programmed to do. This can lead to insufficient sleep, excessive sleepiness, and mood problems, like depressive symptoms.

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What Types of Light Affect Your Sleep? 

Light exposure, especially at night, can seriously disrupt your sleep. Indeed, if your eyes perceive light, your brain will think it is daytime and send a message to your body telling it to stay awake and alert. As you can imagine, this can be problematic if you are trying to get a good night's sleep. Whether you keep a light on a night or have to sleep during the day in a light room, both will make it difficult to achieve deep sleep.

Some researchers investigated the effects of being exposed to light when sleeping. They found that individuals who were exposed to light during their sleep slept on average 10 minutes less than those who slept in a dark room. They were also more likely to be tired during the day and wake up confused throughout the night.

But did you know that not all lights were created equal? Two types of light, in particular, have the power to influence your sleep, blue light, and red light. 

Blue Light 

Smartphones, computer screens, televisions, and the sun all emit blue light. We are then surrounded by blue light all day, every day. If the only source of blue light in the environment was the sun, it would not be problematic. That is because the blue light emitted from the sun helps regulate the internal clock by signaling daytime to the brain.

On the other hand, artificial blue light can make it difficult to fall asleep. The brain cannot distinguish between the blue light coming from the sun and the one coming from electronics. When the brain perceives blue light from electronics, it registers that it is daytime and, consequently, signals to the body that it needs to be awake. This suppresses the mechanisms designed to put us to sleep, like melatonin production.

Electronics are most likely preventing a lot of people from getting a good night’s sleep. Everybody is guilty of spending time on their phones or in front of their computer to relax before bed. A survey indicates that Americans spend on average seven hours every day on their electronic devices. Moreover, nine out of ten individuals admit to spending time on their electronic multiple nights every week, right before bedtime.

Red Light 

Red light has a wavelength of 670 nm, which is longer than blue light (450-495 nm). And, unlike blue light, red light might be helpful for sleeping by causing drowsiness. Indeed, red light wavelengths could help stimulate melatonin production and promote better sleep.

In 2012, a small study investigated the effects of red-light therapy on twenty female athletes. They divided them into two groups: the first one did not do any light therapy, and the second received 30 minutes of red-light therapy every night for fourteen days. They found that the athletes who received light therapy had better sleep quality, higher melatonin levels, and improved endurance performance.

We mentioned earlier that being exposed to light when sleeping could negatively impact sleep quality, but red light does not have the same effect. Unlike other lights, exposure during sleep does not suppress melatonin and might even reduce morning grogginess.

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Tips and Tricks to Minimize the Impact of Light on Your Sleep 

If you are struggling with a sleep-wake disorder or need to sleep during the day, there are things you can do to help you sleep. 

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First, it is best to sleep in a pitch-dark room. Simply closing your eyes is not enough to prevent the light from being sensed by your brain. Therefore, the best way to avoid light exposure is by getting good-quality blackout curtains or roller shade. The Kyle and Bryce Blackout Roller Shade is made from top-quality material and comes in various sizes to fit your windows perfectly. They completely block the outside light to cause a full darkening effect, which will drastically improve the quality of your sleep. Our blackout roller shade could be a lifesaver if you need to sleep during the day as it will make your room completely dark, even if it is daytime. 

Some people cannot fall asleep without having a light on. If this is your case, you should purchase a red night lamp. You should make sure it is the only type of light in your room. A red light will not damage your sleep, and it might even help! 

Second, you should avoid screen time at least 2-3 hours before going to sleep. At the minimum, you should turn down the brightness. Some electronics have a "blue light filter" or "night mode" option, which you should use at night. You can also invest in some blue light glasses if you need to work on your electronics at night. A recent study on 63 individuals found that wearing blue light glasses could improve sleep quality and quantity.

Finally, dim all the lights in your house around bedtime to facilitate the transition between day and night. Use a low-power lamp when getting ready at night to help you relax before bed (1).


A Final Word... 

Circadian rhythms are strongly influenced by natural light and regulate body functions according to the time of the day. One of these functions is the sleep-wake cycle. This cycle can be dysregulated if one person is exposed to too much artificial light at night, especially blue light coming from electronics. Being exposed to light during your sleep can also damage the quality of your sleep and make you tired during the day. The best ways to avoid these problems are to sleep in a completely dark room, avoid screen time at night, wear blue light glasses, and avoid harsh lighting in your home during your bedtime routine.