MacBook 16" M4 Pro (2025 model) running macOS Tahoe 26.1 Reboots when kept idle / sleep for few minutes.

I am experiencing a recurring sleep-related system reset on my MacBook M4 Pro (2025) running macOS Tahoe 26.1. Whenever the device is left idle and enters sleep, it unexpectedly returns to the main login screen. Unlike a normal wake, it asks me to select my user profile and then enter my password, as if the system fully logged out or restarted.

When this happens, all previously open applications and windows are closed, including browsers, documents, and work sessions. However, macOS does not display the usual “Your Mac restarted because of a problem” message after logging in, and no shutdown or crash events are reported in the standard system logs.

Observed Behaviour

• The system repeatedly transitions through various sleep states including Maintenance Sleep, Idle Sleep, Clamshell Sleep, and Notification Wake Back to Sleep.
• Many sleep intervals last only 2–30 seconds, after which the system wakes again.
• These repeated short sleep cycles suggest that the Mac never successfully enters a stable deep sleep state.
• After one of these cycles, the system returns to the full login screen, with all running applications terminated.

Terminal Log Findings

Sleep logs (log show filtered for “sleep”) show:

• Continuous and repetitive entries such as:
  • Maintenance Sleep lasting only 2–8 seconds
  • Idle Sleep lasting a few seconds
  • Notification Wake Back to Sleep
• Occasional long maintenance sleep, but followed again by rapid cycles.

Examples of recent entries:

2025-11-22 22:12:52 Sleep Entering Sleep due to 'Maintenance Sleep' 693 secs

2025-11-22 22:43:43 Sleep Entering Sleep due to 'Idle Sleep' 3 secs

2025-11-23 00:58:37 Sleep Entering Sleep due to 'Clamshell Sleep' 52 secs

2025-11-23 09:52:10 Sleep Entering Sleep due to 'Maintenance Sleep' 917 secs

Shutdown logs (log show --predicate "eventMessage CONTAINS 'Previous shutdown'") show:

• No entries at all, indicating:
  • No forced shutdown
  • No kernel panic
  • No recorded abnormal restart event

I'm not sure if the system is performing a silent logout, an unlogged restart, or a WindowServer-level reset that closes all applications without generating crash reports normally associated with system failures.

Impact

• Loss of all open work, requiring manual reopening of every application.
• Interrupted workflows whenever the Mac enters sleep for more than a few minutes.
• Unpredictable system behaviour that mimics a reboot without logging one.

I just hope Apple fixes this in the next update.

I had this issue from the day I upgraded to 26.0.

And it's not fixed in 26.1.

The previous MacOS was better that way. :/