The Science of Light and Mind and its Affect on Sleep

Smartphones, streetlights, computer screens and televisions keep our world in a perpetual state of brightness and this habitual light exposure affects human mental health.

Light is a crucial factor in regulating the circadian system and the biological clock. Proper exposure to natural light helps synchronize our biological clock with the day-night cycle, promoting better sleep. Conversely, inadequate light exposure, especially in the blue light spectrum, can desynchronize the circadian rhythms, leading to sleep disturbances. Humans (and animals) need both light and dark to function properly.


The world’s largest study on light exposure and its impact on sleep, physical activity and mental health was conducted by Monash University in Australia in 2023. With almost 87,000 participants, the study found that increased exposure to light at night increases a person’s risk for psychiatric disorders such as anxiety, bipolar and PTSD severity as well as self-harm.

Importantly, the study also found that increasing exposure to daytime light can act like a non-pharmacological means for reducing psychosis risk.

In the people exposed to high amounts of light at night, the risk of depression increased by 30% – while those who were exposed to high amounts of light during the day reduced their risk of depression by 20%. Similar patterns of results were seen for self-harm behavior, psychosis, bipolar disorder, Generalized Anxiety Disorder, and PTSD.


Our brains evolved to work best with bright light in the day and with almost no light at night. However, modern, industrialized times have literally turned our biological systems upside down - especially in the past few decades with the introduction of LED’s and blue spectrum light.

In another, yet smaller study, research shows that adolescents who live in urban areas that have high levels of artificial light at night tend to get less sleep and are more likely to have a mood disorder relative to teens who live in more rural areas with low levels of night-time light.

These findings indicate that the simple practice of avoiding all light at night and seeking brighter light during the day could be an effective, non-pharmacological means of reducing serious mental health issues in all ages.


Because humans today challenge this biology, spending approximately 90% of the day indoors under artificial lighting (which is too dim during the day and too bright at night), our biological clock is skewed, confusing our bodies and making us unwell.


Circadian Disruption

According to Scientific Journal PNAS, sleep, circadian rhythms, and mental health are reciprocally interlinked. Circadian disruption, can lead to sleep disturbances, depression and anxiety.

Light's impact on the circadian system is critical, as insufficient exposure to the right light at the right time can desynchronize the biological clock, leading to physiological, neurobehavioral, and sleep impairments. The circadian and homeostatic systems must align for optimal sleep, with sleep pressure building throughout the day and the circadian system signaling wakefulness during the day and sleepiness at night.


Getting your ‘Beauty Sleep’

The phrase of “getting your beauty sleep” has been around a long time. But getting a good nights rest is not all about beauty as new studies have proven. A natural hormone involved in this process is called melatonin which is produced in the Pineal Gland. Melatonin production is influenced by light (particularly blue spectrum light), or lack thereof. Melatonin signals sleep onset in humans and in animals. The circadian system is particularly sensitive to blue light, with peak sensitivity around 460 nanometers (nm).

Artificial or synthetic Melatonin is one of the fastest selling sleep-aids in the United States, according to the Nat’l Institute of Health and poison-control centers have seen an uptick in reports of children ingesting too much.


The Benefits of Light Therapy

The biological clock relies heavily on the daily light-dark cycle to synchronize with the solar day. This synchronization influences sleep-wake cycles, body temperature, hormone production, and alertness. ‘Light Therapy’ has been proven to help with all types of mental illnesses. Below is a list of ways to improve mental health through light. A Harvard Study also found that light therapy helps ease Seasonal Affective Disorder (SAD) as well as perinatal depression.

10 Ways to Improve Sleep Quality with Lighting Alone


  1. Morning Sunlight Exposure: Start the day with a walk in nature: exposure to natural sunlight in the eyes (and Pineal Gland) will help reset the biological clock.

  2. Use Bright Light in the Morning: Use bright, cool-colored blue spectrum lightbulbs in the morning to promote wakefulness. See links below.

  3. Avoid Blue Light at Night: Reduce exposure to cool-colored blue light from phones, computer and TV screens (LED lights) at the very least two hours before bed.

  4. Dim Evening Lighting: Use dim, warm-colored lights in the evening to signal to your body that it’s time to wind down. Kitchen lights are notorious for being too bright - so dim, or turn off, the overhead lights immediately after dinner!

  5. Consistent Lighting Schedule: Maintain a consistent lighting schedule to help regulate your sleep-wake cycle. Go to bed and awake in the morning at the same time every day.

  6. Outdoor Time During the Day: Spend time outdoors during daylight hours to increase exposure to natural light. Spending time in nature has been proven to boost mood.

  7. Install Adjustable Lighting: Use lighting systems, or “Smart Lighting”, which can adjust in intensity and color temperature throughout the day. See links below for certain circadian products.

  8. Bedroom Darkness: Ensure your bedroom is completely dark and cool (temperatures between 63-70 degrees) during sleep by using blackout curtains or an eye mask. Remove all technology - phones, routers, modems and TV’s from the bedroom as these give-off electromagnetic frequency.

  9. Nightlights: Use dim, red or amber-colored nightlights if needed for navigating at night to minimize melatonin disruption.

  10. Light Therapy: If an outdoor walk is not possible then consider using special light therapy bulbs in the morning, especially during winter months, to compensate for reduced daylight exposure. Special bulbs today can also help reduce migraines, increase focus and even improve skin cell renewal.


US Brands that specialize in Circadian Lighting Products

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