When it comes to identifying important external factors that affect the quality of sleep, light invariably tops the list. The kind of light to which you are exposed during the day and the daily light exposure levels are proven to have a profound impact on the quality of sleep you get. Light affects your sleep-wake cycle and circadian rhythms that govern your body clock and govern the level of alertness you have while you are awake.
How Does Light Influence On Sleep?
The human biological clock and sleeping patterns have evolved by the regular pattern of sunlight during the day and darkness at night. However, the availability of electricity and availability of lights 24 x 7 has led to a change in the way humans sleep and the quality of sleep they enjoy.
The constant presence of artificial light right from roads, to offices, to homes, and just before sleep from cell phones or television sets has led to a modern sleep problem as well. It is extremely important to understand different ways how light impacts your sleep and make amends in your lifestyle and bedroom conditions to ensure a good nights’ sleep.
According to research conducted by Stanford University, School of Medicine, people who have been exposed to light just before sleep 10 minutes get less sleep on average compared to others and have reported higher levels of fatigue and impaired functioning during the day.
Here are the ways light influences sleep:
Circadian Rhythm – A small part of the brain named the circadian pacemaker controls the internal clock of the human body which coordinates various body functions, moods, mental health, and so on. Exposure to light greatly influences the functionality of this pacemaker. The circadian rhythm is generally synchronized depending on the sunrise and sunset.
As light enters your retina, the pacemaker interprets this as day and adjusts bodily systems and organs like the day and during the night when light doesn’t fall on the retina, the systems are adjusted as per night. However, too much exposure to light or poorly timed exposure to light alters the circadian rhythm of the body and misaligns the day-night schedule of your body. Exposure to bright light during the night unnecessarily alerts your body and disrupts your sleep schedule. The more light you are exposed to the less sleep you get.
This disruption of your circadian rhythm through disruption of sleep can lead to health impacts like Depression, Obesity, Accidents, Chronic Illnesses like diabetes, and other disorders.
Melatonin Production – Melatonin, also referred to as sleep hormone is known to facilitate sleep. This is produced naturally by the pineal gland inside the brain during evenings when your body is not exposed to light. In fact, as soon as the gland is exposed to light, it stops the production of melatonin. So, too much exposure to light at night results in low production of melatonin resulting in sleep-related disorders like Delayed Sleep-Wake Phase Disorder (DSWPD) and so on. This phenomenon of reduction of melatonin is also observed when you experience jet lag because of traveling to multiple time zones.
Sleep-Wake Cycle –Exposure to light is known to disturb your cycle as well. Normally, your sleep consists of 4-6 sleep cycles with each sleep cycle lasting around 70-120 minutes. Frequent exposure to light may result in disruption of this sleep cycle that can reduce the amount of time you are in deep sleep. This in turn can result in affecting restorative activities of deep sleep like:
- Muscle recovery
- Fight diseases – short term or chronic
- Growth in Children
- Body repair
Types of light impacting your sleep
Different types of light have different illuminance and hence are known to cause a different kind of impact on your sleep. Natural light from the sun has the highest levels of illuminance and hence has the most impact on our body functions. Depending on the wavelength and illuminance, artificial lights affect your body. The blue light that has a short wavelength and is emitted by LEDs is proven to have the maximum impact on melatonin production and your circadian rhythm compared to lights with longer wavelengths.
In general, as a rule, it is better to sleep in as much darkness as possible. You should adjust your bedroom environment to allow low external light to enter your room through dark curtains, low luminance lights, and eliminate screen time just before sleep.
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