Poor sleep is one of the most common complaints after a hip replacement - and it usually improves as the hip settles.
Your surgical team may have told you which positions are fine for sleeping, which side you may lie on, and whether to use a pillow between your legs. Follow their advice. If you were not told, ask at your next contact.
During the day, balance activity and rest: short walks and exercise sessions spread across the day beat one exhausting effort followed by hours on the sofa.