What does the term "Sleep Latency" refer to?

Sleep latency refers specifically to the amount of time it takes for a person to transition from a fully awake state to sleeping. This measurement is critical in sleep studies, as it provides insight into the efficiency and quality of a person’s sleep onset. It is typically measured from the point of lying down to when the individual first enters sleep, often assessed through methods like polysomnography or the Multiple Sleep Latency Test (MSLT). Understanding sleep latency can help in diagnosing sleep disorders and evaluating their impact on daily functioning.

The other answer choices involve different aspects of sleep but do not accurately define sleep latency. Transitioning from light sleep to deep sleep pertains to the stages of sleep that occur after sleep has started, the duration of REM sleep specifically measures the time spent in a particular sleep stage rather than the onset of sleep, and total time in bed before sleeping can vary widely and does not directly indicate how long it took to fall asleep.