Does hair grow faster in the summer?

Hoconnor asks…I’ve always heard that hair grows faster in the summer. Is this true? Why? And if so, is there a way to recreate the summer benefit in the winter (such as with the addition of humidifiers, heat lamps, diet changes?)

The Right Brain responds:

We’ve said this before and we mean it: the members of the Beauty Brains Forum are awesome! After Hoconnor posted this question, SarahF and Lelaleia did some research and found several interesting references. Even though Left Brain admitted to being stumped on this one, these additional resources made us think. That’s the beauty of true science – we’re always glad to reconsider our positions when new data comes in. You can read the entire discussion in the original Forum post, but we’ll recap the highlights here.

Summer time tresses

1. Seasonal Changes in Human Hair Growth

“… The rate of growth of the beard was lowest in January and February and increased steadily from March to July to reach a peak about 60% above the winter level. The rate of growth of thigh hair showed a similar pattern though with less pronounced differences.”

2. Seasonal Variation in Trichogram in Chilean Subjects

“During summer the percentage of telogen increases and the percentage of anagen decreases. This study confirms the presence of seasonal variations in normal trichogram.”

3. Seasonality of Hair Shedding in Healthy Women

“These results confirm the findings of former authors who have indicated seasonal changes in human hair growth, though this is the first study performed systematically in a representative number of women.”

It looks like there is reasonable evidence that hair grows faster in the summer. What an interesting and surprising finding! Isn’t science wonderful?