What are Circadian-Rhythm Sleep Disorders known to disrupt?

Circadian-Rhythm Sleep Disorders primarily disrupt natural sleep schedules and patterns, which are fundamentally tied to the body's internal clock, or circadian rhythms. These rhythms regulate various biological processes, including the sleep-wake cycle, and are influenced by external cues like light and temperature. When a person experiences a circadian-rhythm sleep disorder, their sleep is misaligned with the typical day-night cycle, leading to difficulties in falling asleep, staying asleep, or waking up at appropriate times for daily functioning. This misalignment can significantly affect overall sleep quality, alertness during the day, and various aspects of physical and mental health.

The other options represent factors that could potentially be influenced by sleep disorders but are not the primary aspect that Circadian-Rhythm Sleep Disorders directly disrupt. For instance, body temperature regulation does occur throughout the day and night but is not as directly affected as the primary sleep schedule and patterns. Dream recall ability may vary widely among individuals and is more associated with different sleep stages rather than the timing of sleep itself. Similarly, muscle relaxation during sleep is a normal physiological process that occurs throughout various stages of sleep and is not uniquely disrupted by circadian rhythm issues.