Switch off one light you are not using before you buy anything. NHLBI describes the mechanism plainly: the amount of melatonin in your bloodstream starts to increase in the evening and peaks in the early morning, and exposure to bright artificial light in the late evening can prevent your brain from releasing it. The condition that changes the answer: when the light belongs to a hallway, a housemate or the building across the street, the next step is a conversation or a curtain, not a purchase. Start with the switch.
Look at the room at the hour you actually use it
A bedroom at noon is a different room from the bedroom at 10 p.m. Make the note on an ordinary evening, with the lamps in the state they are usually in.
Count what is on. Not what you own, and not what is off. Include the light coming from a hallway, a neighboring window or a street lamp if you can see it from where you sit. Include a screen only while it is actually in use. NHLBI's page on the sleep-wake cycle is specific about which screens count, naming the light from a TV screen, a smartphone, or a very bright alarm clock as examples of bright artificial light, and noting that internal clocks typically follow a repeating rhythm of about 24 hours regulated by light, darkness and sleep schedules.
Then ask what each source is doing for someone. A lamp may be the only way to read. A hall light may be how another person crosses the house safely.
Map it: source, purpose, control, possible change
Scroll sideways to see the full table →
| Source | What it is for tonight | Who controls it | The change worth asking about |
|---|---|---|---|
| Overhead light | General visibility | You or the household | Is the task it was on for finished? |
| Task lamp | Reading or close work | Whoever is using it | Can it point at the page instead of the room? |
| Hallway light | Getting through the house | A shared decision | Ask before changing it |
| Screen | One named activity | You, or a device setting | End the activity, not the evening |
| Outside light | Not yours | Someone else, or nobody | Record it as a limit; a curtain is the only lever |
The map is not a meter. It records what is on and who decides. It does not measure illumination in lux, specify a color temperature, or give anyone a target.
What is in the bottle you were about to buy
Melatonin is the product most often reached for at this point, and NCCIH's page is worth reading before the checkout. On labeling, a 2023 study found 22 of 25 over-the-counter melatonin gummy products inaccurately labeled, with melatonin ranging from 74 to 347 percent of the labeled quantity, and an earlier study of 31 supplements found 26 percent contained serotonin.
On whether it works for the common case, NCCIH reports the professional guidelines directly: according to the American Academy of Sleep Medicine and the American College of Physicians, there is not enough strong evidence on the effectiveness or safety of melatonin supplementation for chronic insomnia to recommend its use. That is what NCCIH says. It is a reason to try the light switch first, and not a verdict on anyone's prescription.
Change one light, and be able to name it
An example with the clock in it. Bedtime is 10:30 p.m., so NHLBI's advice to use the hour before bed for quiet time, away from intense exercise and bright artificial light such as a TV or computer screen starts the hour at 9:30. At 9:30 the overhead light is on because a task finished at 9:15 and nobody reached for the switch. The change is the overhead off, the task lamp on for reading, and the screen closed when the episode ends rather than when the season does.
One light, one evening. Keep enough light for the things the room has to support: stairs, a bathroom at 3 a.m., a person who moves through at a different hour. Do not cover a vent, change wiring, or improvise with a fixture.
Write down what else changed
Record the adjustment in ordinary words: the overhead light went off at 9:30, the reading lamp stayed on. Then add the rest of the evening honestly, because one night contains a dozen variables and naming the other things that changed is what keeps a note from becoming a claim.
You may find the real constraint is a streetlight, a shared hallway or a shift schedule, and that no switch in your hand reaches it. That is a finished map. The two useful follow-ups are separating the pause you want from the sleep you need and deciding what job the phone has in the room, which is usually the brightest object in it.
Sources and further reading
- How Sleep Works: Your Sleep/Wake CycleAccessed 2026-09-17
- Sleep Deprivation and Deficiency: Healthy Sleep HabitsAccessed 2026-09-17
- Melatonin: What You Need To KnowAccessed 2026-09-17