Final answer:
Stage 1 sleep is where individuals commonly believe they were just dozing or thinking when woken, likely due to the presence of alpha and theta brain waves resembling relaxed wakefulness.
Step-by-step explanation:
The stage of sleep where 7 out of 10 people think they were just dozing or thinking, not sleeping, when woken up is likely to be stage 1 sleep.
This is the first stage of sleep, occurring as a transitional phase between wakefulness and sleep. During stage 1 sleep, brain activity is marked by alpha and theta waves.
Alpha waves are associated with a state of relaxation that is close to wakefulness, which may explain why individuals woken during this stage often believe they were not fully asleep.
Furthermore, stage 1 sleep is characterized by a slowdown in respiration and heart rate and can transition quickly back to wakefulness, making it the period during which individuals are most likely to report they have not been sleeping.