Is this an asian myth or sound advice?

I read this article from DKSH Malaysia, a leaflet given to me in the hospital discharge bag, regarding the topic above.

Should we heed Asian confinement beliefs? Many women who undergo confinement are advised not to shower or wash their hair during the first two weeks, or up to forty days after delivery. The belief is a woman’s body is much weaker after delivery. Symptoms like headache, arthritic pain of the joints and general body aches may occur during older age. To be safe than sorry, many mothers choose to heed the practice of not washing their hair for the first two weeks.

As for me, I sweat a lot and I cannot stand not washing my soiled, smelly and itchy head. I washed my hair with hot herbal water on the fourth day itself and another time on the 15th day. The night after I washed my hair for the first time, I had terrible headache. I told the confinement lady the next morning and she said because I washed my hair and “wind” had entered into my head. Well, I don’t believe this. As for me, I believe it was due to lack of sleep continuously for the past few nights. If washing hair really caused headache, then why I didn’t have headache the second time I washed my hair.

What is your belief? Do you heed the practice?