is also when dreams may feel more vivid. The original article notes that REM sleep often appears more frequently during the final third of the night, around the early morning hours.
This means that if something disturbs your sleep around 3 AM, you may wake up more easily and remember it more clearly.
Stress and an Active Mind
One common reason people wake up around 3 AM is stress. During the day, you may stay busy and distracted. But at night, your mind has fewer distractions, so worries can rise
