Denon AVR-S660H 5.2-Channel Network A/V Receiver - Manual (Page 107)

Sleep timer function
.
SLEEP
You can have the power automatically switched to standby once a set time
has elapsed. This is convenient for viewing and listening while going to
sleep.
0 The sleep timer can be set by pressing SLEEP on the main unit.
Contents Connections Playback Settings Tips Appendix
107
Front panel Display Rear panel Remote Index