It is habitually suggested to sleep with your hair up. Experts have found that when your hair rubs against your pillow, it leads to mechanical damage to it. In other words, it can cause your hair to fray and start to break. Over time, your hair will start to become weaker and weaker. This issue is compounded if you’ve used chemical treatments on it (like bleaching it or coloring it), if you heat style often, or if you have hair that’s naturally more fragile (like curly hair). If this sounds like you, then it’s best to sleep with your hair up to help avoid this damage. To double down on the benefits of wrapping your hair, it’s maybe a smart idea to buy yourself a silk or satin pillowcase.