The scientific reason you get lines on skin during a nap but not a full sleep is mind blowing

Have you ever woken up from the best sleep ever, with a load of lines all over your skin? It’s almost like a badge of honour, to know you just napped real hard. Well, there’s actually *science* behind why you only get those lines on your skin during a 10/10 nap, and not a full sleep at night.

A tweet went viral recently, asking the question. “Why does this only happen during short naps and never after a long sleep?” it said. Attached were a bunch of the sort of lines and marks I mean. There are even entire Reddit threads discussing it. So, obviously, I looked it up. And the answer has fully blown my mind.

Why does this only happen during short naps and never after a long sleep? pic.twitter.com/5dGqW4kzUH

— Out of Context Human Race (@NoContextHumans) June 8, 2026

Why do you get lines on your skin during a nap, but not a full night’s sleep?

It turns out, there are a bunch of scientific reasons as to why this happens during a nap but not overnight. The first answer is quite obvious, but it’s because you move less during a short nap.

When you sleep briefly, you lock into position. So, you put pressure on the pillow, or wherever you’ve fallen asleep, causing fluid displacement. Overnight however, natural tossing and turning movements will distribute that pressure.

As per Laser Doctors, these marks are called sleep lines (or pillow prints) and happen due to four main things:

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• Extended Compression: Staying in one position compresses the skin and restricts local blood flow, creating visible indentations.

• Movement: During a full night’s sleep, you naturally shift positions, whereas a quick nap keeps your face or body pinned in a single fold.

• Dehydration: Skin is more prone to temporary indentations when it lacks optimal hydration or elasticity.

•  Collagen and Elastin Loss: As skin naturally ages, it loses its ability to bounce back as quickly from prolonged pressure.

So, that’s what causes them, and the short answer as to why you don’t get them overnight is because you’re moving about more, so you’re not in position for long enough to cause the pressure marks.

There are other explanations too, such as during a nap you might be sleeping somewhere else to your bed, where there are more things that could leave indent marks. And your quality of sleep is probably lower, and you might be sleeping out of your usual, comfortable bed position.

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