Sangean DDR-31BT (V1) - Manual (Page 28)

7
Sleep timer
Your clock radio can be set to turn off after a preset time has elapsed.
The sleep timer can be adjusted between 5 and 90 minutes in 5
minutes increments (except 75 minutes). Ensure your clock radio is
switched on.
. Press and hold down the Sleep button until desired sleep time appears
on the display. Release the Sleep button.
. The display will show an “ “ indicating sleep timer is set.
3. Press and release the Sleep button to monitor remaining sleep timer
time.
4. To cancel sleep timer, simply press the On / Standby button.
Note:
The Sleep button is on the remote control only. The unit does not has a
Sleep button.