The secret: rinse your hair with cold water for a few seconds after showering. You may have heard this advice in passing, perhaps without thinking about it, but do you know how important this step really is?

If not, here’s a quick explanation: the cuticles of your hair make up the outermost layer of the strand, and they overlap a bit—like shingles on a roof. Heat and steam can open up those cuticles and make it easier for moisture to penetrate (which is where hot oil treatments made their mark), but if they’re left up, your strands will be more prone to breakage and frizz.

Cold water closes the hair cuticles and helps lock in moisture in the strands themselves (plus, it helps the scalp retain moisture as hot water can strip away its precious oils). “The cool water temperature closes and strengthens the hair cuticle, which can lead to stronger, healthier hair over time,” celebrity hairstylist Andrew Fitzsimons previously told mbg about the benefits of cold showers.

He especially recommends pairing the cold jet with deep conditioning treatments (like hair masks) because you want to lock all those five-star nutrients into the hair shaft right away.