# Your Phone Is Stealing Your Sleep

Published March 2026 • 5 min read
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### Key Takeaways

- Blue light (450-490nm) suppresses melatonin production by up to 50%
- Even dim screen light delays your circadian rhythm by 1-2 hours
- Blue-blocking glasses reduce melatonin suppression significantly
- Night mode on devices helps but doesn't eliminate the problem

Your body has an ancient internal clock calibrated to natural light cycles. When the sun goes down, darkness triggers melatonin production, preparing you for sleep. But screens — phones, tablets, laptops, TVs — blast your eyes with blue-spectrum light that tells your brain it's still daytime. The result: delayed, disrupted, and degraded sleep for billions of people.

## How Blue Light Disrupts Sleep

Your eyes contain specialised cells called intrinsically photosensitive retinal ganglion cells (ipRGCs) that detect blue light (around 450-490nm wavelength) and signal your suprachiasmatic nucleus — the master circadian clock in your brain. When these cells detect blue light, they suppress melatonin production from the pineal gland.

Research from Harvard Medical School showed that blue light suppresses melatonin for about twice as long as green light and shifts circadian rhythms by twice as much. A study in PNAS found that reading an iPad for 4 hours before bed (compared to a paper book) suppressed melatonin by 55%, delayed the melatonin onset by 1.5 hours, and reduced next-morning alertness — even after 8 hours in bed.

## The Cascading Effects

Delayed melatonin doesn't just make it harder to fall asleep — it compresses your sleep architecture. When you fall asleep later but still wake at the same time, you lose the REM-heavy sleep that occurs in the final hours of the night. Over time, chronic melatonin suppression is associated with increased cancer risk, metabolic dysfunction, and mood disorders.

Children and teenagers are especially vulnerable because their lenses are more transparent, allowing more blue light to reach the retina. The explosion of screen time among young people correlates with a dramatic shift in circadian timing — they're going to bed later, getting less sleep, and suffering the cognitive and emotional consequences.

## Practical Solutions

The simplest solution: no screens for 1-2 hours before bed. If that's not realistic, use blue-blocking glasses (look for lenses that block wavelengths below 500nm — the orange or amber-tinted ones, not the clear 'blue light' glasses marketed online, which block almost nothing).

Enable night shift or night mode on all devices — it helps but doesn't eliminate the problem. Dim your home lighting in the evening and consider switching to warm-tone (2700K or below) bulbs. If you must use screens, reduce brightness to the minimum comfortable level. The most effective high-tech solution is using e-ink devices (like Kindle Paperwhite with frontlight off) for evening reading.

#### Who Is This For?

Anyone interested in evidence-based longevity strategies, health optimisation, and understanding the latest research on ageing and healthspan.

#### Consult Your Doctor If...

You are pregnant, breastfeeding, taking prescription medications, or have a pre-existing medical condition. This content is educational and does not replace professional medical advice.

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Medical Disclaimer: This content is for informational purposes only and does not constitute medical advice. Always consult with a qualified healthcare provider before starting any new supplement or making changes to your health regimen.

#### Sources & References

1. PNAS - Evening Use of Light-Emitting eReaders
2. Harvard Health - Blue Light and Sleep
3. Journal of Biological Rhythms - Light Spectrum and Circadian Disruption
4. Current Biology - ipRGCs and Non-Visual Light Responses