The Link Between Insomnia and Cognitive Function September 9, 2026 The Link Between Insomnia and Cognitive Function We’ve all experienced that foggy feeling after a restless night. You might lose your train of thought mid-conversation, struggle to focus on work or find yourself rereading the same sentence several times. When poor sleep becomes an ongoing problem, these effects may become more noticeable. Insomnia involves persistent difficulty falling asleep, staying asleep or getting restorative sleep, along with problems functioning during the day. While researchers are still uncovering exactly how insomnia affects the brain, evidence suggests it may influence several areas of cognitive function. Why does sleep matter for your brain? Sleep might feel like your brain is switching off for the night, but it’s actually a busy period of recovery and processing. Throughout the night, we cycle through different stages of non-rapid eye movement (NREM) and rapid eye movement (REM) sleep. These stages support important cognitive processes, including learning and memory. Sleep helps the brain process new information, strengthen memories and prepare for the demands of the following day. When sleep is repeatedly disrupted, the brain may not have the same opportunity to complete these restorative processes. Why can thinking feel harder after poor sleep? Difficulty concentrating is one of the most reported daytime problems among people with insomnia.1 You may find it harder to stay focused on a task, switch your attention when needed or think clearly when there are distractions around you. Memory can also be affected. Working memory allows you to briefly hold and use information, such as remembering instructions while completing a task. Research into insomnia and memory has produced mixed results, but some studies have identified mild difficulties with working memory and other aspects of memory.1 Then there’s executive function, the set of mental skills we rely on for planning, reasoning, multitasking and adapting when circumstances change. Again, research findings are mixed, but some studies suggest insomnia may make more cognitively demanding tasks harder.1 What about your long-term brain health? Researchers are also investigating whether chronic insomnia could have longer-term consequences. A recent study of older adults found that chronic insomnia was associated with a 40% higher risk of developing cognitive impairment and with a faster decline in overall cognitive performance.2 Other research has linked insomnia with changes in areas of the brain involved in memory and higher-level thinking.1 However, this doesn’t mean that having insomnia will cause cognitive decline. The relationship is complex, and more research is needed to understand exactly how the two are connected. Give your brain the rest it needs Healthy sleep is an important part of looking after your brain. Keeping consistent sleep and wake times, creating a dark, quiet and cool bedroom, limiting caffeine later in the day and reducing screen use before bed can all help support better sleep. If you regularly struggle to fall or stay asleep, or you’ve noticed persistent changes in your concentration, memory or thinking, speak with your doctor. Identifying and treating an underlying sleep problem may help you sleep better while supporting your cognitive health in the years ahead. References 1. Suni, Eric, and Nilong Vyas. “How Lack of Sleep Impacts Cognitive Performance and Focus.” Sleep Foundation, 18 July 2023, https://www.sleepfoundation.org/sleep-deprivation/lack-of-sleep-and-cognitive-impairment. Accessed 11 Aug. 2026. 2) Carvalho, Diego Z, et al. “Associations of Chronic Insomnia, Longitudinal Cognitive Outcomes, Amyloid-PET, and White Matter Changes in Cognitively Normal Older Adults.” Neurology, vol. 105, no. 7, Lippincott Williams & Wilkins, Sept. 2025, https://doi.org/10.1212/wnl.0000000000214155. Accessed 11 Aug. 2026.
