Second Display Support

Sleep, wake and the lock screen

While it waits, the display Mac’s screen sleeps like a monitor’s and wakes when your Mac connects. While a picture is shown, both Macs stay awake.

Applies to both MacsUpdated 5 October 2026

While the display Mac waits

Second Display keeps the display Mac ready for your other Mac. Its screen goes dark after the display-sleep time you set in macOS, and lights up as soon as your Mac connects. Your energy and security settings stay as they are, and on battery the Mac sleeps as usual.

While a picture is shown

Both Macs stay awake, so the picture doesn’t go dark under you. If you put the display Mac to sleep yourself, the connection ends; the Mac you work on says it went to sleep and connects again when it wakes.

When the Mac you work on sleeps

Close the lid or choose Sleep, and the iMac says that your Mac is asleep and “Reconnects when it wakes”. Wake your Mac and the picture comes back by itself.

The lock screen

If the display Mac asks for its password after its screen was off, the lock screen covers the picture. Unlock it to see the picture.
While the Mac you work on is locked, macOS lets no app record its screen, so the picture on the iMac pauses. Unlock your Mac and it carries on. A connection started while it’s locked says “Couldn’t start. Is this Mac locked?”