Key Takeaways
- Circadian light regulates our biological rhythm, crucial for sleep, mood, and overall health.
- Aligning with natural light cycles improves sleep quality, mood, cognitive function, and metabolic health.
- Optimize light exposure by getting morning sunlight, dim light in the evening & reducing evening screen time, and maintaining a regular sleep schedule.
Disrupting your biological rhythm can lead to a series of health consequences, such as sleep disorders, decreased productivity, and overall well-being.
What Is Circadian Light and How Does It Affect the Body’s Rhythms?
These rhythms, known as circadian rhythms, are influenced by our environment’s light and dark cycles.
The Science Behind Circadian Light

At the core of our internal clocks is the suprachiasmatic nucleus (SCN), a group of nerve cells in the brain that act as the master clock.
New Circadian Light Technologies
Three main circadian light technologies are becoming popular lately.
These lighting technologies are crucial for creating environments that support our natural circadian rhythms in the absence of constant natural daylight:
- Dynamic Intensity: Intensity tuning refers to adjusting light brightness levels to suit specific needs or times of the day. This concept is crucial in circadian lighting systems as it helps mimic the natural variation of daylight and ensures you get bright days and dim nights.
- Color tuning: Color tuning, or color temperature tuning, involves adjusting the color temperature of the light. The color temperature is measured in Kelvin (K) and can range from warm (yellow/red tones) to cool (blue/white tones). Light frequency, measured in nanometers (nm), can also represent color. This measurement indicates whether the light has longer or shorter wavelengths. By adjusting these frequencies, we can mimic the natural shifts in light from sunrise to sunset.
- Time-specific lighting: Scheduling light changes to align with natural circadian cycles. For example, bright, blue-enriched light during the daytime and dim, warm light in the evening.
How Circadian Light Affects the Body

Sleep Patterns
One of the most noticeable effects of circadian light is on sleep patterns.
Exposure to natural light during the day helps to synchronize our circadian rhythm with the 24-hour day, which helps you feel awake in the morning and prepares your body for sleep at night.
Conversely, excessive exposure to artificial light, mainly blue and bright light from screens, can suppress melatonin production, which might cause difficulty falling asleep and poor sleep quality. (unless you are trying to stay awake and move your sleep to a later hour).
How can you improve these sleep patterns?
Start your day by getting at least 20-30 minutes of natural sunlight soon after waking up.
In the afternoon, spend as much time as possible in natural light. If you work indoors, take frequent breaks to walk outside.
A great natural hack is to expose yourself to sunset, which can reduce the negative effects of bright artificial light at night (e.g. TV or smartphone screens).
Hormone Release
Circadian light also affects the release of various hormones in your body.
For example, cortisol, the hormone that keeps you awake during the day, peaks in the early morning.
Similarly, circadian rhythms and light influence the timing of other hormones, such as insulin, which regulates blood sugar levels.
Insulin is arguably one of the most essential hormones, as disrupting these rhythms can contribute to metabolic disorders like obesity and diabetes.
Digestion and Metabolism
The timing of light exposure also plays a role in digestion and metabolism.
Our digestive system is tuned to be more active during daylight hours when food intake typically occurs.
Circadian rhythmicity influences the timing and efficiency of digestive processes, including the production of digestive enzymes and the absorption of nutrients.
A misaligned circadian rhythm can lead to digestive issues and metabolic syndrome.
Mood and Mental Health
Circadian light significantly impacts mood and mental health.
Daily exposure to natural light helps balance neurotransmitters like serotonin, which affect mood and emotional well-being.
Conversely, lack of natural light and chronic exposure to artificial light at night are linked to increased risks of depression, anxiety, and other mood disorders.
Seasonal Affective Disorder (SAD) is a prime example of how reduced daylight during winter months can lead to depression.
Immune System Regulation
Circadian clocks influence the immune system by regulating immune cell production and release timing.
Studies show that disruptions in circadian rhythms can impair the function of immune cells such as T cells and natural killer cells.
This can lead to increased susceptibility to infections and reduced effectiveness of vaccines.
Cognitive Functions
Light exposure, mainly blue and bright light, affects cognitive functions by regulating melatonin and cortisol levels. Light exposure during the day enhances cognitive performance by improving alertness and concentration.
Studies have demonstrated that disruptions in circadian rhythms can lead to cognitive impairments, such as reduced attention, slower reaction times, and poorer memory.
Cardiovascular Health
Circadian rhythms are crucial in cardiovascular functions by regulating heart rate and blood pressure.
Research indicates that blood pressure and heart rate follow a circadian pattern, peaking during the day and dipping at night.
Disruptions in these rhythms, often caused by irregular light exposure, are associated with increased risks of hypertension, heart attacks, and strokes.
This explains why there’s a higher incidence of strokes and heart attacks in the morning hours, particularly during the shift to daylight saving time.
How to Align with Circadian Light Cycles
Aligning your daily routines with circadian light cycles can significantly enhance your health and well-being.
Here are some practical tips to help you optimize your light exposure throughout the day:- Morning light exposure: As soon as possible after waking up, expose yourself to natural sunlight. Aim for at least 20-30 minutes of outdoor light. This helps reset your internal clock and signals to your body that it’s time to be awake and alert. For example, a morning walk or having breakfast near a window are effective ways to get this exposure.
- Maximize daylight exposure: Spend as much time as possible in natural light throughout the day. Take regular breaks to go outside or sit near windows. Consider using light therapy glasses to mimic natural daylight for those in environments with limited natural light.
- Evening light reduction: Reduce exposure to artificial blue light from screens (phones, tablets, computers, and TVs) in the evening. Use features like “night mode” or blue light filters on your device to minimize their impact. Blue light can suppress melatonin production, and increase alertness which makes it harder to fall asleep. Dim the room lights and ensure you are not in a bright environment.
- Optimize your bedroom for sleep: Ensure your bedroom is dark, cool (e.g. 18-19°C is recommended but this is individual), and quiet. Use blackout curtains to block external light in case you are getting bright light too early (e.g. in the summer when bright light can be hours ahead of your wake-up time), and remove or minimize electronic devices that emit light. A sleep-friendly environment facilitates better sleep significantly.
- Keep a consistent sleep schedule: Go to bed and wake up at the same time every day, even on weekends. This consistency reinforces your circadian rhythm and improves overall sleep quality.
Case Studies on Circadian Light

Understanding the practical implications of circadian light in our daily lives can be challenging without looking at real-world examples and case studies.
Here, we look at a notable experiment that highlights the impact of circadian light on health and well-being.
The Effects of Circadian Light in the Workplace
A recent study from the University of Illinois at Urbana-Champaign and Northwestern University revealed significant benefits of natural light exposure in office environments.
Office workers with access to natural light slept 46 minutes longer on average, had better sleep quality, and experienced improved physical activity and overall quality of life compared to windowless environments.
This study highlights the importance of designing office spaces that maximize natural light exposure to enhance employee health and productivity.
The study measured light exposure, activity, and sleep using actigraphy, a method involving a wrist-worn device that records motion and light exposure.
The results indicated that employees with windows in their offices received 173% more white light during work hours than those without windows, highlighting the critical role of natural light in regulating circadian rhythms and promoting health.
Improve Your Bodily Rhythms with Proper Circadian Light
Understanding how circadian light works is crucial to avoid serious health issues and sleep disorders.
Try the tips in this article and see how they improve your overall well-being.
While this article provides general tips, for personalized circadian light guidance tailored to your specific needs, consider using apps or tools designed for your particular circadian health and chronotype.
If you found this article helpful, check out our other content on the blog.