The icon is an emoticon type face that is representing a sleeping person or sleepy emotion. The face has closed eyes and turned down mouth with an overall is calm expression.
This Sleeping icon is made in Material Design style
developed by Google. This style is based on extremely simplified shapes, thin two-pixel lines, and is optimized for 24x24 px. Unlike other vector icon packs that have merely hundreds of icons, this icon pack contains 6,000 icons, all in the same style and quality.