coconut oil on hair????

So ive heard from many people + online that sleeping with coconut oil on ur hair overnight and washing it out the next day makes it look more voluminous and healthy. I just want to know if this is true and has anyone else tried it?

Also, if you have tried it, was your hair still oily after washing it? Ive done this with tea tree oil last time and it stayed oily for like a week. If you have any recommendations or tips please let me know. Thanks in advance!