Commentary: Joint effect of sleep duration and sleep quality on self-rated health among Canadian adults: estimating relative excess risk due to interaction from a nationwide survey

Sleep duration and sleep quality are well-established determinants of overall health. Extensive evidence showing that inadequate or poor-quality sleep increases the risk of cardiovascular disease, metabolic disorders, mental-health problems, and all-cause mortality (1)(2)(3) . Additionally, recent umbrella reviews and population-based studies confirm that both short sleep and poor sleep quality independently and jointly contribute to adverse physical and psychological outcomes, including depression, anxiety, chronic pain, and reduced subjective well-being (4)(5)(6) .In light of this, we express concern about the methodological integrity of the recently published study by Kader et al. (2025) (7) , "Joint effect of sleep duration and sleep quality on self-rated health among Canadian adults: estimating relative excess risk due to interaction from a nationwide survey." It analysed data from the Canadian Community Health Survey to assess joint effects of short sleep (