Example of a Typical 8-Hour Sleep Cycle on a Hypnogram

A researcher examines a graph plotting an adult's progression through the different sleep stages over an entire night. The graph shows that the individual spends the first half of the night primarily in the deepest, slow-wave stage of sleep. In the second half of the night, the time spent in this deep stage decreases significantly, while the periods of sleep characterized by rapid eye movements and vivid dreaming become longer and more frequent. What is the most accurate interpretation of this graphical data?

A sleep researcher is analyzing a chart that graphically represents a healthy young adult's progression through the different stages of sleep over an eight-hour period. The researcher notes that the first three hours of sleep are characterized by long, consolidated periods of deep, slow-wave sleep (Stage 3), while the last three hours show progressively longer periods of REM sleep and very little time in deep sleep. Based on this analysis, what is the most appropriate conclusion?