If your Galaxy S21 screen goes dark while you are not using it, increase Screen timeout. If bedtime settings activate on a schedule, turn off Sleep mode. They are separate controls, so choose the fix that matches what your phone is doing.
First, identify which setting is causing the problem
| What you notice | Likely setting | Where to change it |
|---|---|---|
| The display turns off after you leave the phone idle. | Screen timeout, the inactivity timer. | Settings > Display > Screen timeout |
| Bedtime-related appearance or actions activate, often at a set time. | Sleep mode, a scheduled or manually enabled mode. | Settings > Modes and Routines > Sleep |
| The display behavior changes when battery saving is enabled. | Power saving options may be affecting display settings. | Settings > Device care > Battery > Power saving |
Samsung notes that available screens and settings can vary by device, software version, and market. If a label differs on your S21, look for the corresponding setting in the named section.
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Make the Galaxy S21 screen stay on longer
For a display that turns off simply because the phone has been idle, increase its Screen timeout:
Recommended Free Tools
- Open Settings.
- Tap Display.
- Tap Screen timeout.
- Select a longer duration from the choices shown on your phone.
AT&T confirms this path for the S21. Samsung Canada documents supported screen-timeout choices from 15 seconds to 10 minutes, but the intervals available can vary. Use the options actually displayed on your device; Samsung says the timeout cannot be disabled completely.
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Turn off Sleep mode and stop it from returning
If the issue is a bedtime mode rather than an idle display timer, turn off Sleep mode:
- Open Settings > Modes and Routines > Sleep.
- On the Sleep mode screen, tap Turn off.
Samsung’s general Galaxy guidance says to tap Turn off at the top of the screen. If Sleep mode activates again, review its schedule or automatic start conditions and change or remove the trigger you do not want. The exact screen presentation can vary with the S21’s software version.
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Check Power saving if the display setting keeps changing
If the behavior occurs only while Power saving is active, inspect its options at Settings > Device care > Battery > Power saving. Verizon’s S21-series guide says configurable options can include setting screen timeout to 30 seconds and turning off Always On Display. The available options depend on the phone’s configuration and software, so check what is enabled on your S21.
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