Why Your Phone Is Ruining Your Sleep
Blue Light - The Sleep Enemy
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You check your phone one last time before bed, just a quick scroll. Maybe you're catching up on messages, watching TikToks, or reading the news. Then you lie awake wondering why you can’t fall asleep.
Spoiler: It’s not just what you're watching, it’s how your screen works. More specifically, it’s the blue light being beamed into your eyes, confusing your body into staying alert.
Let’s break down the science behind blue light, its effect on your circadian rhythm, and most importantly, what you can do to sleep better starting tonight.
What Is Blue Light and Why Should You Care?
Blue light is part of the visible light spectrum, the same one that makes up all the colours we can see. But blue light has a shorter wavelength and higher energy than other types, which is why it’s so stimulating to the brain.
We get the most blue light from sunlight exposure. This exposure causes a boost in alertness, supports memory and mood, and regulates our body clock. But the modern world has introduced artificial blue light into our lives through: Phones ,Laptops, TVs, LED and fluorescent lighting, Tablets and e-readers.
In other words, we’re now exposed to blue light long after the sun has gone down, and that’s where the issues begin.
How Blue Light Disrupts Your Sleep
1. It Suppresses Melatonin
Melatonin is the hormone that helps your body prepare for sleep. It starts rising in the evening as it gets dark and peaks during the night.
However, when you stare at a screen late into the evening, blue light tricks your brain into thinking it’s still daytime, which in turn reduces melatonin levels and makes it harder to fall asleep.
A Harvard study found that exposure to blue light suppressed melatonin for twice as long as green light, and shifted circadian rhythms by up to 3 hours.
“Blue light has a dark side.” — Harvard Health
2. It Shifts Your Circadian Rhythm
Your circadian rhythm is your internal 24-hour clock. It regulates sleep-wake cycles, digestion, hormone release, body temperature, and even your immune system.
When blue light delays your melatonin release, it pushes your entire circadian rhythm later, making you feel sleepy at the wrong times and groggy when you wake up.
Picture your circadian rhythm as a very old delicate pocket watch you carry around with you. Left alone in your pocket it tells the time reliably and accurately. But take it out of your pocket and give it a shake; it quickly loses the time, the minute hand moves sluggishly and suddenly what was once precise becomes uncertain.
Continually “shaking the pocket watch” can add up, contributing to chronic fatigue, brain fog, poor mood, and even metabolic issues. Or in other words, a broken clock.
How Bad Is It Really?
The Sleep Foundation reports that 90% of people in the UK use screens within an hour of bedtime. 90%...that probably includes you.
Regular screen exposure before sleep is linked to less REM (rapid eye movement) sleep, increased sleep latency (time it takes to fall asleep), and nighttime awakenings
A 2020 review published in Nature linked blue light exposure to disrupted circadian signalling and increased risk of depression and weight gain
The bottom line: screens are affecting your sleep more than you think, and it's not just a personal problem, it's a societal one.
How to Block Blue Light and Improve Sleep Quality
1. Use Blue Light Filters on Your Devices
Night Shift (iPhone/iPad) – Go to Settings → Display → Night Shift.
Android – Use built-in Night Mode or download the Twilight app.
Laptops – Install f.lux (free) to auto-adjust screen warmth based on time of day or use the native settings.
These small changes won’t block all blue light, but they’re a simple start.
2. Wear Blue Light Blocking Glasses (Especially After Sunset)
Studies show that blue light blocking glasses worn in the evening can improve sleep quality and melatonin levels. Look for amber-tinted lenses that block 90–100% of blue light in the 400–500nm range.
Recommended: [Top-Rated Blue Light Glasses in the UK] (Affiliate link)
3. Replace Harsh Lighting with Warmer Bulbs
Your room lighting matters as much as your screens.
Use red or amber LED bulbs in your bedroom or bathroom.
Avoid daylight bulbs or bright white LEDs after 7 PM.
Consider smart lighting that adjusts automatically in the evening.
Recommended: Top No Blue Light Bulbs UK
4. Set a Screen Curfew
Try turning off all screens 60–90 minutes before bed. Instead:
Read a physical book
Stretch or journal
Use a meditation app with audio only
Prepare for the next day (clothes, meals, etc.)
Even if you start just 30 minutes earlier, it can have a noticeable effect on how fast you fall asleep.
5. Use a Sunrise Alarm Clock
Instead of using your phone alarm (which also means your phone is switched on, probably on your bedside table, next to your head, ALL NIGHT). Try a sunrise alarm clock that mimics dawn light to wake you more gently and naturally.
This helps reset your body clock from both ends, morning and night.
Recommended: [Best Sunrise Clocks for Biohackers and Light Sleepers] (Affiliate link)
What If I Work Late or Can’t Avoid Screens?
Not everyone can switch off early, especially if you work nights, have kids, or use devices to wind down (a book is much better in my opinion). In that case:
Prioritise blue light glasses, screen filters & warm lighting.
Use dark mode on apps and websites.
Adjust your screen brightness to the lowest comfortable level (Android has an extra dim setting too).
Aim to expose yourself to natural light in the morning to help realign your rhythm.
Every small adjustment adds up.
Final Thoughts: Master Your Light to Master Your Sleep
In the biohacking world, few things are as foundational, or as overlooked, as light hygiene. You don’t need to ditch your phone. You just need to respect the natural rhythms your body evolved with.
Blue light isn’t evil. But at the wrong time, in the wrong amount, it becomes a silent assassin of your sleep, energy, and recovery.
Start small. Reduce evening light. Give your brain the darkness it needs.
Your body will thank you in the morning.
References
1. Harvard Health – “Blue Light Has a Dark Side”
Covers the effects of blue light on melatonin and circadian rhythm.
Link: https://www.health.harvard.edu/staying-healthy/blue-light-has-a-dark-side
2. Sleep Foundation – Light and Sleep
Provides an overview of how light exposure affects sleep timing, latency, and quality.
Link: https://www.sleepfoundation.org/physical-health/how-light-affects-our-sleep
3. Nature – Blue-Light Effects on Circadian Timing and Health
A comprehensive 2020 review article detailing how blue light affects circadian signalling, sleep, and metabolism.
Link (abstract): https://www.nature.com/articles/s41598-020-67244-0
4. Study: Blue Light Exposure Delays Melatonin and Sleep Onset
Specific study showing how different light wavelengths affect melatonin levels.
Link (PubMed): https://pubmed.ncbi.nlm.nih.gov/22564492/
