Black Screen for Sleep

How to use it

1. Pick a sleep timer, for example 30 minutes, or Off.
2. Pick a sound if you want one and set the volume. Tap a sound to hear it straight away.
3. Turn on the dim clock if you want to see the time.
4. Press Start: go black. The screen goes black and the timer starts.
5. To leave, press Esc, or tap the screen and use the dim Exit button in the bottom right corner. A tap on the black screen does not exit, so a sleepy touch will not light up the page.

Turn your device brightness all the way down before you start. On a phone, plug it in if you plan to play sound all night.

How dark is a black screen, really?

• OLED screens (most recent iPhones, many Android phones, some laptops and TVs) switch black pixels off. A black page on OLED gives off almost no light.
• LCD screens (most computer monitors, many tablets and older phones) have a backlight that stays on behind the black. In a dark room the screen looks dark gray and may glow at the edges.
• A screen that is switched off is darker than either. If you do not need the clock or the sound, the darkest choice is to let the screen turn off.

A web page cannot switch your screen off by itself. What it can do is ask the browser to keep the screen awake, and stop asking. That is how the timer works: when it ends, the page releases the screen and your device's own auto-lock setting takes over.

Keep the screen awake: Auto, Always or Never

• Auto (the default) keeps the screen on only while a sound is playing or the clock is showing. On many phones, sound from a web page stops when the screen locks, so the page has to keep it on for the sound to continue.
• Always keeps the screen on while the page is open, even with nothing showing.
• Never lets your device sleep on its normal schedule.

The status under the preview tells you what the page is doing right now. Some browsers do not support keeping the screen awake; the status says so, and you can set a longer auto-lock in your device settings instead.

White, pink, brown noise and rain

All four sounds are made in your browser from random numbers, so nothing is downloaded and they loop without a gap.

• White noise has equal energy at every frequency. It sounds bright and hissy, like a TV between channels.
• Pink noise has less energy as the pitch goes up. It sounds softer and fuller, like steady wind.
• Brown noise drops off even faster, leaving a deep rumble, like a distant waterfall.
• Rain is soft filtered noise with thousands of tiny random bursts mixed in, which sounds like rain on a roof.

The sound fades out over the last 1, 5 or 10 minutes of the timer, so it does not stop suddenly.