Adults

require 6 to 8 hours per night; sleeping over 9 hours is universally

recommended for cognitive restoration.

Adults

require 5 to 7 hours per night; sleeping over 9 hours is proven to eliminate

insulin resistance.

Adults

should sleep 7 or more hours per night on a regular basis; sleeping over 9

hours may be appropriate for young adults or those recovering from sleep debt,

but otherwise its health risk is uncertain.

Adults

require exactly 8 hours per night; sleeping over 9 hours increases

cardiovascular mortality by 50% in all populations.