What term describes the natural bodily changes that follow a daily pattern and can affect alertness?

The term that describes the natural bodily changes that follow a daily pattern and can affect alertness is "circadian variations." Circadian variations are part of the circadian rhythm, which is a biological process that operates on roughly a 24-hour cycle. This rhythm influences sleep-wake cycles, hormone release, body temperature, and other bodily functions, impacting an individual's alertness and overall well-being throughout the day.

Circadian rhythms are primarily influenced by external cues such as light and darkness, which help regulate the body's internal clock. Understanding circadian variations is essential in fields such as occupational health and fitness for duty assessments, as they can greatly affect performance, mood, and cognitive functions.

Other terms like hormonal changes and neurotransmitter fluctuations relate to specific biochemical processes that can occur independently of the daily cycles, while metabolic rhythms generally pertain to energy expenditure and metabolism rather than the broader alertness effects linked to circadian patterns.