research summary

Sleep Disorders Contribute to Cognitive Decline in Women With MS

Obstructive sleep apnea (OSA) is highly prevalent in people with multiple sclerosis (MS) and is the main contributor to fatigue in this patient population.1 Researchers have found that sleep disorders—such as OSA—play a role in cognitive decline in women with MS.2

The researchers analyzed data from the 2013 and 2017 waves of the Nurses’ Health Study (n = 63,866), a long-term study with a focus on risk factors of chronic illnesses in women. Tiffany J. Braley, MD, MS, and her team sought to determine the “direct and indirect longitudinal associations between sleep disorders and perceived cognitive dysfunction in women with MS.”

Within their data uses, all diagnoses and symptoms were self-reported, including those with MS (n = 524). Researchers utilized a composite score of four memory items and binary outcomes to assess cognitive function. Moderating and mediating effects of diagnosed or suspected OSA, sleepiness, and insomnia between MS and cognition were estimated using the four-way decomposition method.

According to their data, in 2013, the prevalence of diagnosed and suspected OSA, sleepiness, and insomnia was higher for nurses with MS. Further, in 2017, nurses with MS were more likely to report cognitive difficulties. In interaction analyses, the researchers found that OSA accounted for 34% of the total effect between MS and participants following instructions. Insomnia mediated 5.4% to 15.1% of the total effect between the disease and following instructions, conversations and plots, and memory impairment. Sleepiness mediated 8.6% to 12.3% of the total effect for those exact outcomes.

“Our results highlighted important pathways between sleep and perceptions of cognitive function in women with MS. We have previously identified important associations between objective cognitive performance and sleep in people with MS, but little is known about how sleep and MS interact together to impact long-term cognitive outcomes, particularly among women who are less likely to be diagnosed with sleep disorders,” Dr Braley said in a press release.3



  1. Braley TJ, Segal BM, Chervin RD. Obstructive sleep apnea and fatigue in patients with multiple sclerosis. J Clin Sleep Med. Published online February 15, 2014. doi:10.5664/jcsm.3442
  2. Braley TJ, Shieu MM, Zaheed AB, Dunietz GL. Pathways between multiple sclerosis, sleep disorders, and cognitive function: longitudinal findings from The Nurses’ Health Study. Mult Scler. Published online January 12, 2023. doi:10.1177/13524585221144215
  3. Insomnia, sleep apnea contribute to reports of cognitive decline in women with multiple sclerosis. News release. University of Michigan, Michigan Medicine; March 15, 2023. Accessed June 6, 2023.