American College of Lifestyle Medicine (ACLM) Board Practice Exam

In late sleep, particularly during the REM (Rapid Eye Movement) stage, significant physiological changes occur, impacting various bodily functions. Increased melatonin levels contribute to a state of deeper sleep, which is crucial for restorative processes. Additionally, during this late sleep phase, the body temperature regulation shifts; however, it is characterized by a gradual decrease in core body temperature as the body prepares for waking.

The answer indicating decreased melatonin levels and increased core body temperature is not aligned with the physiological realities of late sleep. During this time, melatonin levels typically remain elevated, promoting further sleep, while core body temperature actually decreases, which helps facilitate the sleep cycle and the necessary rest for overall health.

In contrast, increased melatonin levels are associated with the progression into late sleep, correlating with decreased blood pressure due to the overall relaxing effects of sleep. Therefore, the most accurate representation of physiological changes in late sleep involves the interplay between melatonin levels, blood pressure, and thermoregulation, aligning closely with the restorative functions of deep sleep and REM periods.