How Does Light Affect Sleep?

The Impact of Lighting on Sleep Health

Man on phone with blue light

Sleep is a fundamental factor in our overall wellbeing. During sleep, our bodies recover, repair, and rejuvenate, playing a critical role in both physical and mental health.

However, the majority of us struggle to achieve the quality sleep we need. And one of the biggest factors that significantly impacts our sleep is light exposure.

Light is a powerful environmental cue that regulates our internal body clock. Our circadian rhythms dictate our sleep-wake cycles, hormonal balances, and numerous other physiological processes. When our exposure to light is misaligned with our natural circadian rhythms, it can profoundly disrupt our sleep patterns, leaving us feeling exhausted, unfocused, and potentially contributing to more severe health issues.

Understanding How Light Affects Sleep

The science behind how light affects sleep and our circadian rhythms is fascinating and multifaceted. Our bodies rely on a complex system of light-sensitive cells in the retina, which communicate with the suprachiasmatic nucleus (SCN) in the brain. The SCN acts as our body's master clock, regulating various hormonal and physiological processes, including our sleep-wake cycles.

During the day, exposure to natural daylight triggers the SCN to suppress melatonin production, promoting wakefulness and alertness. As the sun sets and light levels decrease, the SCN signals the pineal gland to release melatonin, inducing feelings of sleepiness and preparing our bodies for rest.

However, artificial light, particularly blue light from electronic devices and certain light bulbs, can disrupt this delicate system. When our eyes detect blue light in the evening hours, it tricks the SCN into thinking it’s still daytime, delaying melatonin release and making it more difficult to fall asleep.

The importance of sleep health cannot be overstated. Chronic sleep deprivation or poor sleep quality has been linked to a wide range of health issues, including obesity, cardiovascular disease, impaired cognitive function, and increased risk of depression and anxiety.

By understanding how light affects our sleep and taking steps to manage our exposure, we can improve our overall sleep health and reap the numerous benefits of quality rest.

Understanding the Types of Light

Light comes in various forms, each with its unique impact on our bodies. Daylight consists of a complete spectrum of colors and intensities that vary throughout the day, evolving from the warm hues of sunrise to the cooler and more intense tones of midday before returning to warm tones in the evening.


Warm lighting has a Kelvin value typically falling within the range of 2700K to 3000K. This lower Kelvin value results in warm, yellowish hues. The color temperature of warm white light evokes a cognitive sense of relaxation and comfort.

In contrast, cool lighting has a higher Kelvin value, ranging from 3500K to 4100K or higher. This higher Kelvin value gives cool light a brighter, more bluish appearance. The color temperature of cool white light promotes a sense of clarity and alertness.


Natural Light vs Artificial Light

Natural light serves as a critical synchronizer for our circadian rhythms. Our bodies have evolved to respond to the natural ebbs and flows of daylight, signaling when it's time to wake up, be active, and prepare for rest.


On the other hand, exposure to artificial light, especially at night, can disrupt our natural sleep-wake cycles if not managed properly. Many artificial light sources, such as fluorescent bulbs and electronic devices, emit specific wavelengths of light that can suppress the production of melatonin, the hormone responsible for regulating sleep.

As our lives become increasingly indoors, our exposure to natural sunlight has been replaced by much more artificial lighting. And this can have a profound impact on our health.


Blue Light

One of the most significant culprits of sleep disruption is blue light. This high-energy, short-wavelength light is emitted by many electronic devices, including smartphones, tablets, computers, and televisions. Blue light mimics the effects of daylight, tricking our bodies into thinking it's still daytime, even when it's well past sunset.


In the evening, the natural progression toward sleep is orchestrated by a decline in ambient light levels and a shift in the color temperature of light to warmer tones. This is a signal to our body to start winding down, promoting the production of melatonin. Blue light, particularly from screens and certain artificial lighting sources, can disrupt the melatonin release, making it difficult to fall asleep and maintain a restful sleep cycle.

When we continue to be exposed to excessive blue light after sunset, our body interprets this as a prolonged daytime, suppressing melatonin production and delaying the onset of sleep. 

Red Light

In contrast to blue light, red light has been shown to have a less disruptive effect on our sleep patterns. With its longer wavelength and lower energy, red light is less likely to interfere with melatonin production and our circadian rhythms. Research suggests that exposure to red light in the evening hours may even promote better sleep by creating a calming, relaxing environment, leading to the development of red light therapy lamps and nightlights.

Red light therapy

How Low Quality Sleep Impacts Your Overall Health

The effects of disrupted circadian rhythms can cause more than just sleep problems. Negatively impacted sleep health can substantially affect our physical health, productivity, mood, productivity, mental health conditions, and a range of other health issues.

Adequate and quality sleep is linked to improved cognitive function, emotional stability, and a bolstered immune system. It also plays a critical role in maintaining a healthy metabolism and preventing chronic health conditions, such as cardiovascular diseases.

Disruptions to our circadian rhythms result in sleep disturbances, insomnia, mood imbalances, health issues such as impaired cognitive function, digestive issues and daytime fatigue, difficulties with memory and concentration, and many more detrimental impacts to our physical and mental health.

Adequate, high-quality sleep is a cornerstone of good health. 

Best Practices for Sleep Health at Home

1. Natural Light Exposure

One of the best ways to support healthy sleep patterns is to prioritize exposure to natural daylight during the day. Open curtains and blinds to let in sunlight, or spend time outdoors whenever possible. This natural light exposure helps synchronize our circadian rhythms and promotes wakefulness during the day, making it easier to feel sleepy at night.

2. Warm, Dimmable, Indirect Night Light

When it comes to nighttime lighting, opt for warm, dimmable, and indirect light sources. These types of lights emit longer wavelengths that are less disruptive to melatonin production and sleep. Consider using warm-toned light bulbs in the 2700K to 3000K range, and install dimmer switches to gradually reduce brightness as bedtime approaches.

Indirect lighting, such as lamps or wall sconces that diffuse light, can create a cozy and relaxing atmosphere in the bedroom without the harsh glare of overhead lights.

3. Bedside Reading Lights

If you enjoy reading before bed, invest in dimmable bedside reading lights with warm-toned bulbs. These focused lights provide just enough illumination for reading without flooding the room with bright light that could disrupt your sleep.

4. Reducing Blue Light Exposure

In the hours leading up to bedtime, make a conscious effort to reduce your exposure to blue light-emitting devices. Disable night mode or blue light filters on your devices, or consider investing in blue light-blocking glasses if you must use screens in the evening.

5. Considerations for Using Red Light

For additional support for better sleep, red light therapy or red-toned nightlights can be a useful tool. These gentle, long-wavelength lights are less likely to suppress melatonin production and can create a calming environment conducive to rest.


Tips for Melatonin Regulation

A foundational practice to support healthy melatonin regulation and sleep cycles is establishing a consistent sleep-wake schedule, even on weekends. Another is to make sure you create a dark, cool, and quiet sleep environment. Consider using blackout curtains or eye masks to block out external light sources, and invest in white noise machines or earplugs to minimize disruptive sounds.

Luxury bedroom with gold bedspread and warm light lamps

Utilizing Smart Lighting Solutions

Smart lighting technology has opened up new possibilities for optimizing our sleep environments. With programmable smart bulbs and systems, you can automate your lighting to gradually transition from bright, cool tones during the day to warm, dimmed lighting in the evening, mimicking the natural cycle of sunlight. Some advanced systems even allow you to schedule specific color temperatures and brightness levels throughout the day, ensuring your exposure to light is aligned with your body's natural rhythms.

Start Incorporating Lighting Practices for Sleep Health

In our modern world, where artificial light is ubiquitous, it’s essential to be mindful of how our exposure to different light sources impacts our sleep health. By understanding the science behind light and its effects on our circadian rhythms, we can make informed choices to optimize our sleep environments.

Prioritizing natural daylight exposure during the day, minimizing blue light in the evening, and creating a sleep-friendly environment with warm, indirect lighting can go a long way in supporting quality rest and overall wellbeing.

Remember, sleep is not a luxury; it’s a fundamental necessity for our physical and mental health – and our goal for our indoor indoor lighting practices is to harmonize with the natural light cycles that are beneficial to our body and circadian rhythms as much as we can.

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