When it comes to washing our hair, we're normally told that heat is bad. Blow drying or straightening your hair can strip your locks of its natural oils, dry out the cuticle and causing breakage and frizz - but a hair expert says this is wrong.
Content creator Abbey Yung, who is currently in training to get her trichology certificate, has revealed she stumbled on some mind blowing information while studying.
While we're lead to believe we should be avoiding heat at all costs, Abbey claims letting your hair fully air dry can be more damaging.
In a recent video on her @abbeyyung TikTok page, the content creator shared: "You will never air dry ever again after I tell you this."
She then pointed to a piece of research which was published in 1981 and presented at the Annual Meeting of the American Oil Chemists' Society.
Abbey continued: "In that journal I found one of the most mind blowing sentences I've ever read about hair science.
"It says 'hair dried in air lost its sebum, or oil, at a slower rate than hair dried with a -hot-air dryer'.
"So if you've ever wondered why your hair doesn't seem to get greasy as quickly when you blow dry it versus when you air dry it, this is exactly why."
According to Abbey, your hair will naturally lose excess oil in other ways, but blow drying your hair essentially kickstarts it.
Answering someone who was still confused by the science jargon, Abbey replied: "Losing sebum at a slower rate = more sebum left on the scalp!"
Abbey added that you lose 40-60% of the sebum a few days after from brushing your hair, sleeping on a pillow, or other ways, but using a blow dryer makes it happen faster.
Because too much heat still isn't good for your hair, Abbey tends to air dry 80% of the way, and then "blow dry the rest". She added: "You can also just blow dry your roots!"
The video has now been seen by more than 850k people, and many were blown away by finally realising why their hair gets greasy more quickly by letting it air dry.
One person said: "That makes so much sense! I've always noticed the difference but never knew why."
Another added: "So here I thought I was doing my hair a service by not blow drying it and that's what is causing my hair to be so greasy after a day!"
A third said: "That is so true! I've always wondered why I can go with more days between washes when I blow dry it! But I don't have time to do it every time."
Do you let your hair air dry or do you use a hairdryer? Let us know in the comment section below.
