Brightness and standby
The backlight: how bright it is while someone uses the screen, and how it dims when nobody does.
Brightness
The backlight while the screen is in use. 5 to 100 %, in steps of 5 on the screen and in Tessera, in steps of 1 through the Home Assistant entity Normal brightness. Default 100 %.
Lowering it pulls the standby and night brightness down with it: those two can never be higher than the normal brightness.
Auto standby
On, the screen dims by itself after Standby after without a touch. Off, it stays on until Sleep is pressed from Home Assistant. Default on.
Turning it off wakes a screen that was in standby.
Standby after
How long the screen waits without a touch before it dims. From 1 minute to 24 hours; default 10 minutes. The − and + keys walk in bigger steps as the time grows: half minutes, then minutes, then quarters and halves of an hour.
The time counts from the last touch. Opening a card, the settings page or a page from an automation counts as a touch; a Wake from Home Assistant restarts the count too.
Standby brightness
The backlight in standby, outside the night hours. 0 to 100 %, never above the normal brightness; default 20 %. At 0 the backlight is off and the glass is black.
The tiles stay on the glass in standby, dimmed. A screensaver can take their place.
On a screen whose backlight has no levels this row is a switch: Screen on in standby.
Waking up
Any touch wakes the screen. The first touch only wakes: it doesn't switch the lamp under your finger, so you can't switch something by accident in the dark. The one exception is a page that is a single full-page switch tile, which switches on the wake tap, like a wall switch.
Also wakes the screen: the Wake button of the screen's device in Home Assistant, an alert, an alarm panel going off, and an automation that opens a page or the settings page.
Sleep and Wake from an automation
The screen's device has two buttons, Wake and Sleep.
Wake lights a dimmed screen and restarts the standby count. It does not count as a touch for Back to Home, so an automation that wakes the screen on motion doesn't keep a card or a far page open: the screen wakes on the Home page once the time ran out.
Sleep dims the screen at once, also with Auto standby off, and holds it until a tap, a Wake or an alert. A screen asleep shows no screensaver.
Press them with the action button.press on the button's own entity. Don't target the whole device: that presses Wake and Sleep both.
Screens that don't dim
The Waveshare 4.3-inch and 7-inch screens have no standby. Their backlight has no levels, and waking them from dark makes them restart, so they stay lit. They have none of the settings on this page.