The Short Version
The evidence does not support the claim that watching the sunset promotes sleepiness through circadian mechanisms. Peer-reviewed research consistently shows that light exposure in the evening delays circadian timing and pushes sleepiness later, while melatonin—the key sleep-onset hormone—rises under dim or dark conditions, not in response to light. The claim conflates the fact that sunset wavelengths influence circadian brain centers with the unsupported conclusion that sunset viewing actively induces sleepiness. Any benefit is indirect and depends heavily on context.