Yeah, I have a female fren who also got dandruff.. Cause when u sleep late night, u don't wash your hair during the normal time (once every morning/noon etc). Dandruff is caused by oily/dirty/itchy scalp. Altho u sleep late night, try to wash your hair at night (maybe around12am). The objective is too keep your scalp clean 24hrs a day. Just wash anytime u feel ur hair start to itch/oily. (Some girls need to wash twice a day)