okay, i washed every day for the first 2 weeks, but then got worried about mold risk, because they lock up like crazy. so now i also wash twice or 3 times a week.maybe your hair is also thicker on the left side? this is very common. but maybe you're right about which side you sleep on - good luck with that, though, i remember from pregnancies that it's sooo hard NOT to sleep on the side you've always preferred