Sleep affects almost every physiological and psychological process. The body has normal low cycles called circadian rhythm lows. These lows are represented by increased sleepiness. When we do not get enough sleep, our body will physically try hard to make us sleep and psychologically we crave it. As a veteran shift worker, the primary focus of our night shift conversations was comparing how many hours of sleep we had that day.
Prevention is important.
The only cure is sleep. Allow at least 4 hours of uninterrupted sleep each day during sustained operations to maintain minimal performance. 20 minutes or 90 minutes in length. A 60 minute cycle causes waking during the REM cycle of sleep. The person wakes up feeling more irritable less refreshed and disorientated.