Between work, exercise routines, hobbies, and just plain exhaustion, creating—and sticking to—a hair-washing routine can feel like an Olympic sport. Though it’s been hotly debated how often you should wash your hair, another factor to consider is the time of day you choose to shampoo your tresses. Whether you swear by a morning shower to help you wake up and take on the day, or you’re a staunch night shower supporter who needs the wind-down time and extra sleep, the key to knowing the best time to wash your hair lies with your hair type. Here’s what experts had to say.

How does my hair type affect when I should wash my hair?

One of the main factors to consider when deciding when to wash your hair is its thickness, which refers to the diameter of individual strands, and is measured by touch and sight. For example, if your strands are coarser and more opaque, you have thick hair, and if they’re harder to feel and less visible, you have fine hair.

With that in mind, fine hair tends to get oilier faster than thick hair. Since friction with your pillow can activate the sebaceous glands of the scalp, it’s better to wash fine hair in the morning to help ensure it stays clean all day, says Jose Sanchez, a hair master at Oramai Hair Salon in Madrid. Morning washes will also help fine hair maintain volume, María Baras, hairstylist and director of Salon Cheska in Madrid, adds. Those with fine hair should also wash their hair more often to prevent oil buildup, Marisa Garshick, MD, board-certified dermatologist at MDCS Dermatology, previously told Vogue.

On the other hand, those with thick hair can better tolerate washing their hair at night and benefit from less frequent washes, so their hair isn’t stripped of natural oils.

If I wash my hair at night, is it OK to sleep with wet hair?

One caveat to washing your hair at night is the fact that you shouldn’t make a habit of sleeping with wet hair, especially if your hair is straight or wavy.

“Wet hair tends to be more fragile because water temporarily breaks hydrogen bonds in the protein structure of hair strands,” NYC-based board-certified dermatologist Hadley King, MD, previously told Vogue. “This increases elasticity, which can make the hair more prone to breakage.” Though curly and textured hair experiences the inverse when it comes to elasticity and breakage, it’s still not recommended to sleep with wet hair frequently, due to potential disruptions to your head’s microbiome, bacteria growth, breakouts, and scalp conditions.

If you know you’re going to be in a time crunch and won’t have time to dry your hair before sleeping, experts recommend using a satin or silk pillowcase, using nourishing products, and considering styles that help prevent tangles and allow oxygen flow to the scalp, like plaits, braids, or pineappleing, depending on your hair texture.

So, although the time you choose to wash your hair comes down to preference, these factors can help you make more informed decisions about your hair-care routine.

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