# Dim lights and put screens away

Published by Pawel Jozefiak. [About this project](https://healthy100.jock.pl/about/), [How we check sources](https://healthy100.jock.pl/methodology/)

- Canonical: https://healthy100.jock.pl/evening-light/
- Language: en
- First published: 2026-09-27
- Evidence checked: 2026-09-28, using AI-assisted source verification
- Clinical review: Not clinically reviewed
- Number 90 of 100 in the list: https://healthy100.jock.pl/#evening-light

Reducing bright evening light can help your body prepare for sleep.

**The number:** Turn off electronic devices at least 30 minutes before bed ([CDC, 2024](https://www.cdc.gov/sleep/about/))

## The evidence

- Evidence grade: B. Grade B: consistent large cohort studies, with some trial evidence.
- Basis: CDC sleep guidance and NIOSH evidence on circadian responses to evening light
- Outcome: recommended minimum screen-free time before bed
- Comparison: CDC bedtime guidance
- Impact: 39/100. The impact score is an editorial prioritization heuristic for the general list, not a validated estimate of your personal risk.

## Why it matters

Bright light near bedtime can delay the internal clock that helps time sleep. CDC recommends switching off electronic devices at least 30 minutes before bed. This is practical sleep guidance, not a demonstrated percentage reduction in disease risk.

## How to do it

1. Set a reminder to finish screen use before your intended bedtime.
2. Use gentler lighting as bedtime approaches.
3. Choose a quiet activity such as reading a printed book.

## Putting it into practice

### Start now

- 1 minute: Choose when screens will go off tonight, at least 30 minutes before bed, and pick a quiet activity to replace scrolling.
- 5 minutes: Prepare a screen-free bedtime option, such as a printed book, and choose gentler room lighting that still lets you move safely.
- 15 minutes: When bedtime is approaching, start quiet reading with electronic screens put away; keep the lighting comfortable for reading and moving safely.
- 30 minutes: Spend the final half hour before your intended bedtime on a quiet activity without electronic screens, using comfortable, gentle lighting.

### What it looks like

- Swap a last half hour of scrolling for a printed book before bed.
- Choose softer room lighting as your intended bedtime approaches, keeping enough light to move safely.

### Common mistakes

- Putting away your phone while leaving the television on misses another bright screen, so wind down without either.
- Dimming lights so far that you cannot move safely creates a hazard, so retain the light you need.

### A structured start

**Make a quieter end to the day**

1. Stage 1: Choose a realistic time to stop using screens before bed.
2. Stage 2: Prepare a quiet replacement activity and gentler lighting.
3. Stage 3: Try the routine across several evenings and adjust it to fit your life.

### Trusted how-to guides

- [About Sleep: habits and sleep diary](https://www.cdc.gov/sleep/about/), CDC
- [Healthy Sleep Habits](https://www.nhlbi.nih.gov/health/sleep-deprivation/healthy-sleep-habits), NHLBI, NIH

## Sources

- [About Sleep](https://www.cdc.gov/sleep/about/), CDC, 2024 (Tier 1 guideline)
- [Effects of Light on Circadian Rhythms](https://www.cdc.gov/niosh/work-hour-training-for-nurses/longhours/mod2/19.html), CDC NIOSH, 2020 (Tier 1 guideline)

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General health information, not a diagnosis or an individual treatment plan. Personalization changes the order of suggestions; it does not assess your medical risks. Follow the cautions and consult a qualified clinician when needed.

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