Babies cry in their sleep for several common reasons:
- They often cry when transitioning between sleep cycles, particularly because babies spend more time in REM (active) sleep, where they may twitch or cry briefly before settling back to sleep. These sleep cycles last about 40 minutes, and during the brief awakenings between cycles, crying can occur without fully waking the baby.
- Overtiredness can cause babies to cry in their sleep as stress hormones like cortisol are released, making it harder for them to fall and stay asleep.
- Babies may cry in their sleep due to discomfort such as hunger, a wet or dirty diaper, temperature issues (too hot or too cold), teething pain, or other minor irritations.
- Reflexes like the Moro (startle) reflex can cause sudden movements that might make them cry in their sleep.
- Around 6 to 18 months, babies may experience separation anxiety or sleep regressions linked to developmental milestones, which can also lead to crying during sleep.
In many instances, crying during sleep is a form of communication or a reaction to normal sleep processes, not necessarily a sign of distress. Babies often self-soothe and return to sleep after these brief cries.
