Adding the reflexive pronoun to some verbs shifts what they mean rather than just pointing the action back at you. Dormir is to sleep; dormirse is to fall asleep. Ir is to go; irse is to leave. Acostar is to put someone to bed; acostarse is to go to bed yourself.
Examples
- Duermo ocho horas, pero me duermo muy tarde.
- I sleep eight hours, but I fall asleep very late.
- Me acuesto a las once y leo un rato.
- I go to bed at eleven and read for a while.
- Se fue sin decir nada.
- He left without saying anything.
The mistake to avoid
"Me duermo ocho horas" says you fall asleep eight times, not that you sleep eight hours.
Where this fits in
Daily routines & habits, Spanish A2: Talk about what you do every day, what time, and how often. Reflexive verbs and frequency adverbs.