Though getting less than seven hours for one night will not have much of an effect on an individual, if the person chronically less than seven hours, then signs of symptoms will be seen and will likely diminish one's daily functionality, ones cognitive performance, as well as seeing signs of other sleep- deprivation symptoms.
Sleep deprivation is caused by an excessive lack of sleep. There are many symptoms that one might face when one is sleep deprived. According to a board-certified physician Brandon Peters, the most common symptoms are sleepiness throughout one's day, mood changes, difficulty concentrating and impaired performance, memory and thinking problems, disorientation, hallucinations and paranoia (a belief that you are being persecuted by some outside entity), pain complaints, and lastly, a disruption of ones normal sleep cycle.