Sleep is a complex biological process that is essential for good help and proper functioning of the brain. It’s important for all of the cells in your body and the systems in it. There are an array of factors that can affect your sleep, including stress, caffeine and alcohol intake and certain medications. In this article, we will focus on the effects of light on sleep, why it is important to create sleep-friendly environments and uncover more about the sleep-wake cycle regulated by circadian rhythm.

“Sleep is not a waste of time. There is no way to replace it with anything else.”

– Dr Steven Laureys, Neuroscientist, Head of BeSophro Scientific Advisory Board

What is Circadian rhythm?

Circadian rhythms are 24-hour cycles that are part of the body’s internal biological clock, also known as the circadian clock. It’s found in the brain and follows the 24-hour day-night cycle of the earth and is influenced by external prompts, such as light and temperature. This body clock sets the timings for the circadian rhythm, which regulates sleep-wake cycles, hormonal activity, body temperature and eating and digestion.

The sleep-wake cycle is the most important as it helps you to fall asleep at night and wake up in the morning. Any disruptions to this cycle can lead to sleep problems and other health issues in the future. When light enters the eyes, even through closed eyelids while we sleep, it activates particular cells in the back of the retina which send a signal to the circadian clock in the brain. The brain then sends signals throughout the body to alert organs and other systems that it is time to wake up.

In response to darkness, the pineal gland secretes melatonin, an essential sleep-promoting hormone that is key to the regulation of the circadian rhythm and lets the brain know it’s time to sleep. When our body produces melatonin, we begin to feel drowsy, enabling us to fall asleep quicker.

It’s important to create positive sleep habits, such as following a regular sleep schedule, avoiding caffeine and alcohol before bed and creating a relaxing bedroom environment with no screens. However, it’s also very important to get exposure to bright, natural light at the right time during the day, such as in the morning, and limit this exposure at night, especially nearer to bedtime to avoid disrupting the circadian rhythm.

What is the effect of light on the circadian rhythm?

The effects of light on the circadian clock and sleep are all mediated by the retina through photoreceptors. The light/dark cycle of the sun has a powerful effect on the circadian clock and it is most sensitive to light:

  • 2 hours before usual bedtime
  • during the night
  • 1 hour after usual wake-up time in the morning

The circadian rhythm is controlled by a small part of the brain, known as the circadian pacemaker and is highly sensitive to light, such as the intensity, duration and spectral composition. Blue light, from smartphones and laptops, has a shorter wavelength of around 460-480 nm yet it is the most effective light in reducing the amount of melatonin produced, which is key in promoting deep, restorative rest. When we look at our screens at night and before bed, we are changing our sleep architecture and disrupting the circadian rhythm, making it harder to fall asleep and leading to sleep deprivation.

In contrast, exposure to bright light, preferably natural light, in the morning signals the wake cycle and can improve alertness and cognitive performance, as well as uplift our mood. Exposure to sunlight has been shown to have an array of health benefits, such as regulating circadian rhythm and improving mood and immune function.

Why light should be off while sleeping?

Human biology has evolved with sleep following the natural rise and fall of the sun, however, in today’s society, electronics provide constant illumination. As artificial light shines bright all day long, we must be aware that an excess amount or poorly timed exposure can have a huge impact on our sleep as it causes the circadian rhythm to be misaligned with the day-night schedule.

Here are some reasons why we should avoid light while sleeping:

  • Exposure to blue or artificial light during sleep can interfere with your natural sleep cycle and suppress the production of melatonin which helps us fall asleep and stay asleep.
  • In addition to affecting our sleep, exposure to artificial light at night has also been linked to various health problems, including obesity, diabetes, and depression.
  • Light exposure at night can also affect the transition between sleep cycles, affecting the quality of sleep. Too much light can lead to repeated awakenings which in turn interrupts the sleep cycle and reduces the time spent in deeper, more restorative sleep.
  • When your sleep quality and depth are affected you can experience daytime fatigue, irritability, and difficulty concentrating.
  • Light entering the retina activates the parasympathetic nervous system which can disrupt our metabolism if we are still asleep.

What are the benefits of sleeping in a dark room?

Limiting our exposure to light as bedtime approaches has a variety of benefits including:

  • Exposure to natural light during the day can help regulate the circadian rhythm and improves sleep at night.
  • By sleeping in a dark room, you can improve the quality of your sleep, promote melatonin production and wake up feeling more rested.
  • When you get more restful sleep you will notice an improvement in your mood and cognitive function during the day.
  • Optimum sleep quality is important for our brains as while we sleep the glymphatic system removes neurotoxic proteins accumulated during the day. This waste removal from the central nervous system is essential for maintaining the homeostasis necessary for a healthy environment of the brain.
  • Lack of sleep has been linked to an increased risk of chronic diseases such as obesity, diabetes, and cardiovascular disease. When you improve the quality of your sleep by sleeping in a dark room, it may reduce the risk of these chronic diseases.
  • Melatonin is not only important for regulating sleep but it has also been shown to have anti-ageing effects. When your sleeping environment is dark, you are promoting the production of melatonin, leading to potential anti-ageing benefits.
  • Sleeping in a dark room can help reduce your sensitivity to light, making it easier to fall asleep and stay asleep.

How to regulate your light exposure for sleep

There are several steps you can take to regulate your light exposure and improve your sleep quality.

  • Getting light during the day helps to align your sleep-wake cycle with the rising and setting of the sun which can improve the quality of your sleep.
  • Try to stop using electronic devices at least 30 to 60 minutes before going to bed. If you want to use your phone or laptop leading up to bedtime, avoid using them in the bedroom and in bed. Consider wearing blue light-blocking glasses.
  • Keeping light levels dim for two hours before sleeping can help you fall asleep more easily. You can do this by using warm-coloured bulbs and avoiding electronic devices.
  • It’s also important to create a sleep-conducive environment in your bedroom. This includes a cool and dark bedroom, comfortable bedding and keeping noise to a minimum.
  • Try blackout curtains and using a sleep mask to block out any remaining light.

Dr Steven Laureys, Neuroscientist, Head of BeSophro Scientific Advisory Board, explains:

“There shouldn’t be any screens in our sleeping rooms. First of all, the blue light from all of the screens and television will inhibit the production of melatonin that’s being produced in the evening. We don’t want the suppression of that natural sedative hormone. Secondly, if these things are going to excite me or maybe even stress me, it’s going to be more difficult to let go and to enjoy a good night’s sleep.”

– Dr Steven Laureys, MD, PhD

If you have issues with your sleep that affect your energy, concentration or mood, you should talk with your doctor. Sophrology is a mental wellbeing practice that you can follow alongside your doctor’s advice. The short, easy-to-follow exercises blend Eastern wisdom with modern science and combine science-backed modalities such as relaxation, breathing, gentle movement, meditation and visualisation that help balance the body and mind through regulating the nervous system.

When you practice Sophrology, you become aware of the present moment, learn to let go of negative thoughts and emotions, learn how to respond to stressful situations and physically relax both body and mind, which is the key to restful sleep. Sophrology teaches you simple techniques to help you to get to sleep quickly and sleep soundly through the night with just 10-minute practices per day. Sophrology can be introduced to your bedtime routine, as well as limiting light exposure, to prepare you for deep sleep.

When you are mindful of light exposure, you can begin to make small changes to your sleeping habits that not only ensure your circadian rhythm remains in sync but also protects your overall health.

Sleep is a complex biological process that is essential for good help and proper functioning of the brain. It’s important for all of the cells in your body and the systems in it. There are an array of factors that can affect your sleep, including stress, caffeine and alcohol intake and certain medications. In this article, we will focus on the effects of light on sleep, why it is important to create sleep-friendly environments and uncover more about the sleep-wake cycle regulated by circadian rhythm.

“Sleep is not a waste of time. There is no way to replace it with anything else.”

– Dr Steven Laureys, Neuroscientist, Head of BeSophro Scientific Advisory Board

What is Circadian rhythm?

Circadian rhythms are 24-hour cycles that are part of the body’s internal biological clock, also known as the circadian clock. It’s found in the brain and follows the 24-hour day-night cycle of the earth and is influenced by external prompts, such as light and temperature. This body clock sets the timings for the circadian rhythm, which regulates sleep-wake cycles, hormonal activity, body temperature and eating and digestion.

The sleep-wake cycle is the most important as it helps you to fall asleep at night and wake up in the morning. Any disruptions to this cycle can lead to sleep problems and other health issues in the future. When light enters the eyes, even through closed eyelids while we sleep, it activates particular cells in the back of the retina which send a signal to the circadian clock in the brain. The brain then sends signals throughout the body to alert organs and other systems that it is time to wake up.

In response to darkness, the pineal gland secretes melatonin, an essential sleep-promoting hormone that is key to the regulation of the circadian rhythm and lets the brain know it’s time to sleep. When our body produces melatonin, we begin to feel drowsy, enabling us to fall asleep quicker.

It’s important to create positive sleep habits, such as following a regular sleep schedule, avoiding caffeine and alcohol before bed and creating a relaxing bedroom environment with no screens. However, it’s also very important to get exposure to bright, natural light at the right time during the day, such as in the morning, and limit this exposure at night, especially nearer to bedtime to avoid disrupting the circadian rhythm.

What is the effect of light on the circadian rhythm?

The effects of light on the circadian clock and sleep are all mediated by the retina through photoreceptors. The light/dark cycle of the sun has a powerful effect on the circadian clock and it is most sensitive to light:

  • 2 hours before usual bedtime
  • during the night
  • 1 hour after usual wake-up time in the morning

The circadian rhythm is controlled by a small part of the brain, known as the circadian pacemaker and is highly sensitive to light, such as the intensity, duration and spectral composition. Blue light, from smartphones and laptops, has a shorter wavelength of around 460-480 nm yet it is the most effective light in reducing the amount of melatonin produced, which is key in promoting deep, restorative rest. When we look at our screens at night and before bed, we are changing our sleep architecture and disrupting the circadian rhythm, making it harder to fall asleep and leading to sleep deprivation.

In contrast, exposure to bright light, preferably natural light, in the morning signals the wake cycle and can improve alertness and cognitive performance, as well as uplift our mood. Exposure to sunlight has been shown to have an array of health benefits, such as regulating circadian rhythm and improving mood and immune function.

Why light should be off while sleeping?

Human biology has evolved with sleep following the natural rise and fall of the sun, however, in today’s society, electronics provide constant illumination. As artificial light shines bright all day long, we must be aware that an excess amount or poorly timed exposure can have a huge impact on our sleep as it causes the circadian rhythm to be misaligned with the day-night schedule.

Here are some reasons why we should avoid light while sleeping:

  • Exposure to blue or artificial light during sleep can interfere with your natural sleep cycle and suppress the production of melatonin which helps us fall asleep and stay asleep.
  • In addition to affecting our sleep, exposure to artificial light at night has also been linked to various health problems, including obesity, diabetes, and depression.
  • Light exposure at night can also affect the transition between sleep cycles, affecting the quality of sleep. Too much light can lead to repeated awakenings which in turn interrupts the sleep cycle and reduces the time spent in deeper, more restorative sleep.
  • When your sleep quality and depth are affected you can experience daytime fatigue, irritability, and difficulty concentrating.
  • Light entering the retina activates the parasympathetic nervous system which can disrupt our metabolism if we are still asleep.

What are the benefits of sleeping in a dark room?

Limiting our exposure to light as bedtime approaches has a variety of benefits including:

  • Exposure to natural light during the day can help regulate the circadian rhythm and improves sleep at night.
  • By sleeping in a dark room, you can improve the quality of your sleep, promote melatonin production and wake up feeling more rested.
  • When you get more restful sleep you will notice an improvement in your mood and cognitive function during the day.
  • Optimum sleep quality is important for our brains as while we sleep the glymphatic system removes neurotoxic proteins accumulated during the day. This waste removal from the central nervous system is essential for maintaining the homeostasis necessary for a healthy environment of the brain.
  • Lack of sleep has been linked to an increased risk of chronic diseases such as obesity, diabetes, and cardiovascular disease. When you improve the quality of your sleep by sleeping in a dark room, it may reduce the risk of these chronic diseases.
  • Melatonin is not only important for regulating sleep but it has also been shown to have anti-ageing effects. When your sleeping environment is dark, you are promoting the production of melatonin, leading to potential anti-ageing benefits.
  • Sleeping in a dark room can help reduce your sensitivity to light, making it easier to fall asleep and stay asleep.

How to regulate your light exposure for sleep

There are several steps you can take to regulate your light exposure and improve your sleep quality.

  • Getting light during the day helps to align your sleep-wake cycle with the rising and setting of the sun which can improve the quality of your sleep.
  • Try to stop using electronic devices at least 30 to 60 minutes before going to bed. If you want to use your phone or laptop leading up to bedtime, avoid using them in the bedroom and in bed. Consider wearing blue light-blocking glasses.
  • Keeping light levels dim for two hours before sleeping can help you fall asleep more easily. You can do this by using warm-coloured bulbs and avoiding electronic devices.
  • It’s also important to create a sleep-conducive environment in your bedroom. This includes a cool and dark bedroom, comfortable bedding and keeping noise to a minimum.
  • Try blackout curtains and using a sleep mask to block out any remaining light.

Dr Steven Laureys, Neuroscientist, Head of BeSophro Scientific Advisory Board, explains:

“There shouldn’t be any screens in our sleeping rooms. First of all, the blue light from all of the screens and television will inhibit the production of melatonin that’s being produced in the evening. We don’t want the suppression of that natural sedative hormone. Secondly, if these things are going to excite me or maybe even stress me, it’s going to be more difficult to let go and to enjoy a good night’s sleep.”

– Dr Steven Laureys, MD, PhD

If you have issues with your sleep that affect your energy, concentration or mood, you should talk with your doctor. Sophrology is a mental wellbeing practice that you can follow alongside your doctor’s advice. The short, easy-to-follow exercises blend Eastern wisdom with modern science and combine science-backed modalities such as relaxation, breathing, gentle movement, meditation and visualisation that help balance the body and mind through regulating the nervous system.

When you are mindful of light exposure, you can begin to make small changes to your sleeping habits that not only ensure your circadian rhythm remains in sync but also protects your overall health.

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