Gao reads with great interest the article by Puri et at. They provided important evidence that adults with self-reported limitations of physical function (PF) had significantly higher odds of having a doctor diagnosed sleep disorder (SD) compared with those without PF limitation. They also found that 'participants having cognitive problems and cardiovascular and pulmonary disorders as secondary conditions that cause difficulty in PF have 145% and 28% higher odds of having a SD". When defining 'cognitive problems', the authors only considered depression, anxiety, and emotional problems, whereas they failed to take other important neurocognitive issues into account especially cognitive impairment. As the study participants were primarily middle-aged and older adults with a mean age close to 60 years, those with mild or even more severe cognitive impairment might have misreported their physical functioning status and history of SD.