How Long Does A Sparrow Sleep?

At 3.30pm I tuned my telly to BBTV (that's Bird Box TV), sat with a cup of  tea and waited.  My bird tumbled in to her box at precisely 3.50pm.  She fidgeted for a bit, preened, threw out some poo then settled in the corner, face to the wall, head tucked in over her shoulder, so that her feathers made a pretty swirl.  She looked like a wall nut whip with a tail.
I changed channels periodically throughout the evening and watched her sleeping.  You'd think it would be hard to see bird's breaths, but she breathes deeply and her tiny body pulses in and out with some force. 
The following morning, I took more tea into the living room and settled down to watch her wake.  It was getting light by 7.30 but she didn't move.  At 7.45 am, she woke suddenly, shook herself and immediately returned her head to its snoozing position with such force I felt sure she must've stabbed herself with her beak.  She obviously wasn't ready to face the world.  Perhaps she was dreaming of being chased by a sparrowhawk?  Do sparrow's dream?  Then at 7.50 am, she woke, and without any preening or shaking of feathers, just jumped up to the entrance hole and left.  

So, how long does a sparrow sleep?  16 hours!  Even longer than me in the winter!