Hair grows faster in the summer sun: true or false?

Does our hair really grow faster in summer? Or is this a persistent and mistaken belief?
Imagine that the sun and heat during the summer actually accelerate hair growth!

A biological reaction that makes your hair stand on end just thinking about it, leading you to fear increased use of razors and other grooming techniques to get rid of your downy hair? There's no need to worry unduly, since it's been proven that this phenomenon is very slight. The growth may even go unnoticed: over several weeks, it's only a few millimeters.

Blood Circulation and Vitamin D

In fact, summer heat causes blood vessels to dilate, improving blood circulation throughout the body, particularly to the hair roots and scalp, reports RTBF. Improved circulation means boosted hair growth. Furthermore, vitamin D, whose synthesis in the skin is triggered by the sun, also has an impact on the health of our hair, promoting its growth.

(MH with Raphaël Liset - Source : RTBF - Illustration : ©Unsplash)