1. Mac Screen Flashes or Glitches After Sleep? Here’s the Fix ⚡
You open your MacBook or wake your iMac… and the screen flickers. It might flash once, glitch with horizontal lines, or momentarily go black before lighting up. If your Mac screen is flickering on wake, it’s not just annoying — it can signal deeper system or GPU issues.
Don’t panic. Most of the time, this issue comes from macOS sleep settings, GPU handoffs, or software conflicts — not a dying display. Let’s walk through exactly how to diagnose and solve the problem.
2. Common Causes of Screen Flickering After Wake
There are several reasons your Mac might flicker after sleep:
- macOS display bugs or glitches (common after updates)
- External monitors or multiple displays
- Graphics switching (Intel ↔ AMD/NVIDIA or integrated ↔ discrete)
- Resolution mismatches or scaling issues
- Background app conflicts (especially screen recorders or window managers)
3. Try a Full Shutdown (Not Just Restart)
First, shut down your Mac completely, wait 15 seconds, and start it again. A full shutdown clears GPU state data that sometimes causes graphical glitches after sleep.
4. Disable “Automatic Graphics Switching” (If Available)
On MacBook Pro models with dual graphics chips, macOS switches between them based on power usage. This can cause wake flicker.
- System Settings → Battery → Options
- Disable “Automatic graphics switching”
This forces the Mac to use the high-performance GPU at all times — useful for testing the cause.
5. Unplug External Monitors Temporarily
If you’re using an external display (HDMI, DisplayPort, USB-C):
- Disconnect the monitor before putting the Mac to sleep
- Wake the Mac with only the internal screen
If flickering disappears, the issue is tied to display resolution, refresh rate, or handoff timing. Updating monitor firmware or trying a different cable can help.
6. Reset NVRAM and SMC 🛠️
Resetting system controllers can often fix flicker issues:
- NVRAM: Restart → hold
Option + Command + P + Rfor 20 seconds - SMC: Shut down → hold Shift + Control + Option + Power for 10 seconds (Intel only)
On Apple Silicon Macs, shut down fully for 10 seconds and restart — these resets happen automatically.
7. Switch Display Resolution to Force Refresh
Sometimes flickering is caused by a cached resolution glitch. To fix it:
- System Settings → Displays
- Switch to a lower resolution
- Then back to “Default for display”
This resets the render pipeline and clears glitches.
8. Boot in Safe Mode to Rule Out Third-Party Apps
Safe Mode disables login items and extensions:
- Intel: Hold Shift during startup
- Apple Silicon: Hold Power → Options → press Shift → Continue in Safe Mode
If flickering stops in Safe Mode, a background app (like a screen recorder, theme manager, or display manager) is likely to blame.
Extra Tip 💡
Apps like Magnet, DisplayLink, BetterDisplay, or even Zoom (when screen sharing) can leave behind display extensions that cause screen issues. Try uninstalling or disabling them temporarily to test results.
🚀 Fix Wake-Up Flickering with AppHalt
AppHalt prevents display issues by pausing apps and background tasks that cause GPU stress and graphical bugs.
✅ Reduce load before sleep to ensure clean wake
✅ Pause extensions known to conflict with macOS display
✅ Improve performance and stability of animations
📥 Want your Mac to wake up without the flicker? Download AppHalt now and enjoy a flawless screen experience.
