CortexLit

CortexLit tool · Sleep · Runs offline · No account

Evening Dimming Countdown

Build a three-stage dimming sequence counted back from your bedtime, with the clock time for each stage.

← Back to the article · See the evidence

This tool gives general information based on the research summarised in Light in the Bedroom at Night: What the Studies Show. It is not a medical device, does not diagnose, and does not replace advice from your clinician.

Your inputs

Share (opt-in)

Off by default. Anything here is built on your own device and nothing is uploaded. Pick exactly what goes on the card.

Preview of exactly what would be shared:










Free vs Plus




Free (this page)
  • full countdown from bedtime
  • stage-by-stage clock times
  • text export and print
  • all citations and cautions


Plus (optional, one-time)
  • calendar (.ics) reminders per stage
  • unlimited share images
  • share card without the 'Made with CortexLit' footer


Checkout isn't live yet, so Plus is unlocked here with a local code. The check runs in your browser and can be bypassed; it is a placeholder for a real payment link.






Free tier: 1 share image per result.






Commercial disclosure: optional paid Plus tier; all evidence, cautions and the main result are free. No affiliate links, no sponsors.







What this is based on


Every output names at least one verified PubMed source. Identifiers were verified on 2026-10-11 in an earlier batch and carried over into this build; they were not re-queried here, and no retraction database was checked. Verification was at abstract level.


Gooley 2011
Gooley JJ, Chamberlain K, Smith KA, et al. Exposure to room light before bedtime suppresses melatonin onset and shortens melatonin duration in humans. J Clin Endocrinol Metab. 2011;96(3):E463-E472.
PMID 21193540 · randomized controlled trial · weight 0.8 · abstract level
Tähkämö 2019
Tähkämö L, Partonen T, Pesonen AK. Systematic review of light exposure impact on human circadian rhythm. Chronobiol Int. 2019;36(2):151-170.
PMID 30311830 · systematic review meta analysis · weight 1.0 · abstract level


Limits: The controlled study compared ordinary room light with dim light; it did not test a three-stage sequence. The staging here is a practical way to make the change stick, not a tested protocol.







Privacy


Inputs stay in this page's memory. There is no telemetry, no analytics call and no network request. Saving is opt-in, local to this browser, deletable, and unencrypted.