No, lying on one side or the other won’t affect the growth of your hair. Your follicles are pre-programmed to grow in their own unique way, independent of how you sleep. If you’re worried about your hair while you sleep, some experts suggest sleeping on silk pillowcases. Silk has amino acids in common with your hair that won’t strip your hair of moisture. Additionally, silk is less likely to pull and tug your strands, which means your hair will be smoother with less split ends and breakage.