Modern urban environments expose us to constant artificial lighting, making it harder for our bodies to maintain natural sleep-wake rhythms. Streetlights, neon signs, car headlights, and glowing billboards all contribute to light pollution, which can keep our brains wired even when it’s time to rest. In fact, for the first time in human history, more people now live in urban areas compared to rural regions. A 2024 report cited in Brain Science says, about 83 per cent of the world’s population lives in areas that are highly polluted by artificial light. 

But what does this shift mean for our sleep and mental health? Let’s find out. 

 

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The Impact of Artificial Light on Sleep 

You must have known some people who wake up at the crack of dawn feeling refreshed while others go to bed late at night. That’s your chronotype at work, your body’s natural preference for sleeping and waking times. This internal clock isn’t just a personal habit; it’s deeply regulated by light exposure, particularly how and when you encounter natural and artificial light throughout the day.

As a matter of fact, the brain relies on a master clock located in the suprachiasmatic nucleus (SCN) of the hypothalamus. This clock takes signals from light exposure to regulate your circadian rhythm, the 24-hour cycle that controls your sleep-wake pattern, hormone release, body temperature, and even digestion. 

 

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During the morning, light suppresses melatonin, the sleep hormone and increases cortisol, stress hormone to help you become awake and alert. On the other hand, exposure to artificial light especially from screens, LED bulbs, and street lights during night time can disrupt melatonin production. This causes you to stay awake for longer causing difficulty in making you sleep. When this natural cycle is disrupted, it can trigger a range of sleep disorders, mood imbalances, and cognitive issues.

Too much light exposure at night weakens your brain’s ability to process and store information, making it harder to concentrate, remember things, and stay sharp. Students pulling all-nighters under harsh fluorescent lights and professionals grinding away on screens late into the evening are all at risk for brain fog, slower reaction times, and burnout.

It’s not just about being tired. Studies suggest that long-term exposure to artificial light at night can increase the risk of neurodegenerative diseases like Alzheimer’s and dementia. Constant disruption of your circadian rhythm interferes with the brain’s ability to clear out toxins and repair itself during sleep.

 

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Ways to Protect Sleep and Mental Health From Light Exposure

If artificial light is messing with your sleep and mental well-being, it's time to make changes in your everyday routine. This can help reset your body’s natural rhythm, improve sleep quality, and boost your mood. Here’s how:

1. Get More Natural Light & Green Space Exposure: A 2017 study by BJPsych International reveals that spending time outdoors, especially in green spaces. This helps regulate your circadian rhythm by increasing exposure to natural daylight, which boosts serotonin and helps you feel more awake during the day. Try to get at least 30 minutes of sunlight exposure every morning, ideally before 12pm. Apart from  this, take walks in parks, gardens, or any green areas to improve mood and reduce stress.

2. Reduce Screen Time Before Bed: Blue light from screens (phones, laptops, TVs) suppresses melatonin production, making it harder to fall asleep. Turn off screens at least 1–2 hours before bed to let your brain wind down. If you have kids, make them practice too for their better cognitive health. Always use blue light filters or night mode on your devices if you must use them late at night. For light entertainment, listen to audiobooks, podcasts, or physical books instead of scrolling. 

3. Create a Sleep-Friendly Environment: For a sound sleep, use blackout curtains to block streetlights and any outside glare. Opt for warm, dim lighting (red or amber hues) instead of bright white or blue lights. Keep your room cool, quiet, and clutter-free to encourage restful sleep.

4. Choose Smart Human-centric Lighting: Selecting the right type of lighting in your home can make a big difference. A 2023 report by Wipro shows that human-centric lighting can actually help support your natural sleep-wake cycle, boost mood, and improve cognitive function. This approach tailors indoor lighting to mimic natural daylight patterns, reducing the negative impact of artificial light exposure. Use warmer-toned bulbs (yellow/orange/red) in the evening instead of bright white LEDs. Try smart bulbs that adjust color temperature based on the time of day.

5. Regularise Evening Routine for Better Sleep: A relaxing pre-bed routine tells your brain it’s time to sleep. Try relaxing activities like meditation, deep breathing, or journaling before bed. Besides, avoiding caffeine or heavy meals before bedtime can also help in better sleep. Last but not least, follow this routine every day, even on holidays or weekends for better results. 

 

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Light exposure plays a huge role in your sleep, mental health, and brain function. Being mindful of when and how you use artificial light could make all the difference in how you feel, think, and function. By making small, intentional changes to reduce artificial light exposure and increase natural light intake, you can improve your sleep quality, mental clarity, and overall well-being. Prioritising good sleep habits today can protect your brain health for years to come.

 

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