First of all, you shouldn’t wash your wavy hair every single day. It is best to wash it once every 3-4 days or when it gets greasy. To protect your hair during nighttime, you should try one of the following methods: - Try a high yet loose ponytail that starts on the top of your head. It’s also wise to choose a silk or satin pillowcase instead of a cotton one because it can such your hair’s moisture and dehydrate it; - You can also wear it like Heidi, in at least two rope twists because it will provide your hair with definition and protection; - A loose braid is another way to go and avoid wearing a bun because it can make your waves looser than they are. When you wake up, you can apply some sea salt water all over your hair to recover the shape of your curls.