Which state is marked by relatively low levels of physical activity and reduced sensory awareness that is distinct from periods of rest while awake?
1. sleep consciousness
2. circadian rhythm
3. jet lag

The correct answer is 1

Sleep is divided into several phases, each of which has a specific physiological stage. The five stages of sleep form the cycle, lasting about 90 minutes each. In this way, a sleep cycle is repeated four to five times a night.

Basically, we can divide sleep into two phases: REM (Fast Eye Movement) and NREM (Non-Fast Eye Movement). The state of NREM corresponds to 75% of the sleep period, and is divided into four phases.