What is defined as the amount of sleep a person has lost over a period of time compared to what they should receive?

The term that describes the amount of sleep a person has lost over a period of time compared to the amount they should be receiving is "sleep debt." This concept emphasizes the cumulative effect of insufficient sleep, indicating how many hours of sleep a person is lacking relative to their optimal sleep needs. For example, if an individual requires eight hours of sleep per night but consistently averages only six, they accumulate a sleep debt of two hours per night. Over the course of a week, this would amount to a total sleep debt of 14 hours.

In contrast, sleep latency refers to the time it takes to transition from full wakefulness to sleep, sleep quality relates to how restorative or satisfactory sleep seems, and sleep efficiency is a measure of the ratio of total sleep time to the time spent in bed trying to sleep. These concepts, while crucial in polysomnography, do not specifically quantify the shortfall of sleep, which is the key aspect of sleep debt.