Final answer:
A sleep diary is a true, useful tool for the initial assessment of sleep disorders due to its cost-efficiency and ability to record sleep patterns over time, leading to initial evaluations and informing further testing if needed.
Step-by-step explanation:
True: A sleep diary is indeed a useful starting point for the assessment of sleep disorders because it provides a non-invasive, cost-and time-efficient method to gather information on a person's sleeping patterns and habits. Sleep diaries can capture details of bedtime routines, sleep duration, nocturnal awakenings, and perceived sleep quality over an extended period. This personal sleep data is crucial for medical professionals to make an initial evaluation before deciding if further, more intricate tests are necessary. For instance, patterns of insomnia, such as difficulties in falling or staying asleep, can be readily identified through the consistent use of a sleep diary.
In practice, participants may be involved in a study where their sleep patterns are monitored before and after the introduction of a potential treatment, such as new medication. The mean hours slept could be compared in such a scenario, providing data for the assessment of the medication's efficacy. Furthermore, tracking sleep over time can reflect how biological rhythms, including circadian rhythms, impact sleep quality, and can be particularly useful where bright light therapy or similar interventions are being considered for individuals experiencing circadian disruption.