The one type of shampoo that is ruining your hair.

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Finally, researchers have discovered the one thing that really matters in life: bad hair days, and why we have them.

Let’s just pause for a moment to say: THANK YOU, SCIENCE.

A study published in the International Journal of Trichology has found that your shampoo’s pH level is the difference between you having a good hair day and a truly shit one.

Brazilian researchers found that out of the 123 shampoos tested, those with a pH above 5.5 (the pH of the scalp) can cause a buildup of static electricity between individual hair strands. This leads to frizzy, flyaway and generally unmanageable hair.

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“Alkaline shampoos rough up the hair’s surface, causing cracks in the fibre and leaving strands more prone to breakage,” says study author Maria Fernanda Gavazzoni, a professor of dermatology.

Since you probably haven’t thought much about alkaline and acid since Year 9 Chemistry (or ever). Here’s a quick refresher: a pH below 7 is acidic, a pH above 7 is alkaline, and 7 is neutral.

A two-minute hair tutorial for your dirty lob

Most professional and in-salon shampoos are formulated with a lower pH level, which explains why your hair always looks amazing when you step out of the salon, but you can never replicate it at home.

Isn’t this a huge relief? You weren’t just born with crap hair, it’s been your shampoo’s fault this whole time.

If you have chemically treated, coarse, dry or damaged hair from straightening treatments, you want to be especially careful when choosing a shampoo. Damaged hair has less lubrication and a thinner cuticle layer, making it especially vulnerable, says Gavazzoni.

RELATED: 3  ways to curl your hair without a hair curler.

Gavazzoni says women (who want fabulous hair) should drop any clarifying shampoos – which are more alkaline – from their routines, and look for “pH balanced” or “low pH” shampoos. Also worth noting is that conditioners usually have a low pH level, so there’s no need to buy a specific one.

To save your fingertips from Googling “pH balanced shampoos,” we’ve done the ground work and compiled a gallery right here.