No, not at all. When hair is completely wet, it is at its weakest, and sleeping with freshly washed hair can result in strand breakage, increased frizz, and excessive hair fall. To begin, avoid washing your hair at night if at all possible. If you don't have a choice, dry it or at the very least wait until it's only slightly damp before sleeping with it. Also, before going to bed, use a good strengthening leave-in conditioner to make your hair less prone to breakage.