Final answer:
Narcolepsy is the sleep complaint least expected in older adults, as it's typically identified at a younger age, unlike insomnia, sleep apnea, and restless legs syndrome which are more prevalent in the older population.
Step-by-step explanation:
The sleep complaint one would LEAST expect from an older adult is narcolepsy.
This disorder is marked by an irresistible urge to fall asleep during waking hours and is frequently accompanied by cataplexy, which involves muscle weakness or paralysis reminiscent of REM sleep, and sometimes vivid dream-like hallucinations.
While disorders such as insomnia, sleep apnea, and restless legs syndrome are more common in the older population due to various factors including changes in sleep patterns and increased health issues, narcolepsy is less commonly diagnosed in older adults and is typically identified at a younger age.