Which state is marked by relatively low levels of physical activity and reduced sensory awareness that is distinct from periods of rest while awake?

Sleep

Explanation:

It is the state in which the consciousness is altered and is characterised by the following feature

During sleep, there are different changes that occur in the body such as decrease in blood pressure ,changes in the brain activity ,change in the breathing rate and  body temperature.

The amount of sleep needed by an individual changes as the body ages , for example a baby needs more sleep than the adult ,who needs 6-8 hours per day to function properly .