Boss BF-3 Owner's Manual page 13

Enabling Sleep Mode (default setting)
1. Carry out the same procedure as described in steps 1
and 2 under "Disabling Sleep Mode."
2. While continuing to depress the pedal, move the
DEPTH knob so it's within the range illustrated
below.
The CHECK indicator will light.
3. Release the pedal to complete the procedure.
* Battery power continues to be consumed even in sleep
mode. To prevent battery consumption, turn off the power
by removing the plug from the GUITAR IN jack or BASS IN jack.
About Sleep Mode
13