Blue Light Bedtime Calculator
When to stop screens before bed for better sleep.
Enter your values
ⓘ Live results
Results
- Stop screens at
- 21:30
- Last caffeine
- 15:00
- Last large meal
- 20:00
- Dim lights from
- 21:00
Quick answer
Melatonin release is suppressed by evening light, so a screen cut-off 60-120 minutes before bed helps sleep onset.
cut-off = bedtime - recommended lead time
How to use the Blue Light Bedtime Calculator
- 1Enter the bedtime you are aiming for.
- 2Choose a screen cut-off lead of 60-120 minutes.
- 3Dim household lighting at the same time for a stronger effect.
Worked example
Using the values the calculator loads with:
Inputs
- Bedtime hour (24h)23
- Bedtime minute0
- Screen cut-off lead90 min
Results
- Stop screens at21:30
- Last caffeine15:00
- Last large meal20:00
- Dim lights from21:00
Frequently asked questions
Do night-shift filters help?
They reduce blue light but not brightness or mental stimulation — dimming and stopping matter more.
Is 8 hours the right caffeine cut-off?
Caffeine's half-life is about five hours, so eight hours leaves roughly a third in your system.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.