The best app blocker for sleep switches on by itself at bedtime, is hard to undo when you are half asleep, lets you plan nights off, and keeps your data on your phone. Apple Downtime is free, Opal suits daytime focus, and SETL is built bedtime first.
An app blocker, sometimes called a screen blocker app, stops chosen apps from opening at set times. On iPhone they are built on Apple's Screen Time framework.
That framework is designed for privacy. The app receives opaque tokens for the apps you pick, so a well built blocker never learns what you use.
What a sleep app blocker needs to do
Blocking during the day and blocking at bedtime are different jobs. At night, four things matter.
It switches on by itself
If you have to start it, you will not. The block should begin at your bedtime, every night, automatically.
It is hard to undo at midnight
A one tap override is a willpower test you will fail when tired. Look for deliberate friction before an app unlocks.
It understands real life
Nights off for events and shift work, planned in advance, so the rule does not collapse the first time life gets in the way.
It keeps your data on the phone
Your usage patterns are personal. A good blocker processes them on the device and never uploads them.
The main options
Apple Screen Time
Free and already on your iPhone. In iOS 27 its bedtime tool is a Screen Time Schedule; in iOS 26 it was Downtime. When Block at Downtime is off, downtime only shows a reminder, and when you set limits for yourself, you know the passcode.5
Opal
A polished focus app for iPhone, Android and Mac, with a Sleep Mode. Opal Pro costs $99.99 a year, and there is a free plan with one rule.3
Sunbreak
A nightly app blocker that locks apps at bedtime and can alert an accountability partner if you break your pact.4
SETL
Built bedtime first. SETL blocks your chosen apps at the time you set, plans nights off with SETL Plans, and brings the same block into your day with SETL Sessions. $39.99 a year, with 7 nights free.
See the full SETL vs Opal comparison.