The present work must, surely, depict a garzone from Volterrano's studio who has been posed to appear as if asleep: his head tilted back, eyes closed and arms limply resting at his side.
Although there are some clear differences in the pose a tentative connection has been drawn between the present work and the winged figure of Sleep in the fresco of Vigilance and Sleep (fig. 1) which Volterrano painted in the mid 1640s on the ceiling of the Stanza della Guardia in the Villa Medicea di Castello outside Florence.

The subject of the fresco is appropriate for a guardroom. Sleep lies among clouds while a putto holds a poppy under his nose. Above, Vigilance stands alert with a candle and a heron. The pose of Sleep seems to have been inspired by that of the famous antique sculpture known as the Barberini Faun, or Drunken Satyr, which had been discovered in Rome in 1628 (now in the Glyptothek, Munich) and which Volterrano may have known through a print published in 1642. A drawing for the youth standing beside Vigilance is in the Fogg Art Museum, Cambridge, Mass.1
A comparable sheet, though depicting a seemingly older model, was sold in these rooms on 26 January 2011 (lot 541).
1. T. McGrath, 'Preparatory Drawings by Volterrano at the Fogg Art Museum,' Master Drawings, vol. XLIII, no. 4, 2005, pp. 503-5, fig. 5