You have no doubt slept with wet hair at least once out of habit or due to a lack of time. However, does it have consequences on your hair's radiant shine?
During hairwashing, the water makes the hair fibre's keratin cuticles lift and loosen. The protective barrier formed by them is therefore weakened. The hair becomes porous and, as a result, is more sensitive to external damaging factors.
Consequently, the effects of rubbing your head on the pillow, which weakens the hair and encourages knots to form, are much increased on damp hair. As a result, the hair fibre breaks more easily during detangling.
Wrapping your hair in a towel doesn't make going to bed with wet hair any better - quite the opposite. While you sleep, the temperature of your body goes up. As a result, you create a 'sauna effect' which upsets the scalp's balance, making it more liable to get irritated.
By now, you know that sleeping with damp hair is a bad idea. However, if despite all of that, you must (very occasionally) do so, apply a leave-in night treatment from your mid-lengths down to your tips before going to bed. This will work as a protective shield against rubbing and will make detangling easier when you wake up.