When Madhavi first told me this on the altar, I just exclaimed ! "How adorable!" So what every Radha Krishna pujari would know and most other devotees would not know is that, the Lord of the Universe, the controller of everything moving and non-moving, THE Supreme personality of Godhead......sleeps with his flute under his pillow! :)
i.e The pujari who puts the deities to sleep at night usually takes Krishna's flute and keeps it under his pillow physically. I've heard a couple of reasons for this but the official ones from Jananivas prabhu are:
1) The flute is sooo dear to Kanha that he does not want to be separated from it since it is with the flute that he controls the gopis
2) The gopis know that with this flute Kanha controls them so they are always looking to steal his flute. He keeps it under his pillow for protection
Endearing!
nadyas tadā tad upadhārya mukunda-gītam āvarta-lakṣita-manobhava-bhagna-vegāḥ ālińgana-sthagitam ūrmi-bhujair murārer gṛhṇanti pāda-yugalaḿ kamalopahārāḥ
"When the rivers hear the flute-song of Krishna, their minds begin to desire Him, and thus the flow of their currents is broken and their waters are agitated, moving around in whirlpools. Then with the arms of their waves the rivers embrace Murari's lotus feet and, holding on to them, present offerings of lotus flowers."
- Srimad Bhagavatam 10.21.15
"When the rivers hear the flute-song of Krishna, their minds begin to desire Him, and thus the flow of their currents is broken and their waters are agitated, moving around in whirlpools. Then with the arms of their waves the rivers embrace Murari's lotus feet and, holding on to them, present offerings of lotus flowers."
- Srimad Bhagavatam 10.21.15