Insomnia and Sleeping Less Than Six Hours May Increase Risk of Cognitive Impairment

If you’re tossing and turning night after night, you’re far from alone. Between 30% and 50% of adults experience insomnia symptoms at some point, and around 10% go on to develop chronic insomnia.¹ While we often think of sleep as a luxury we can cut back on, new research shows that consistent sleep deprivation—especially getting fewer than six hours a night—may come at a much higher cost: our brain health.²

Insomnia is more than just struggling to fall asleep. According to the DSM-5, it involves persistent dissatisfaction with sleep quality or quantity and results in distress or difficulty functioning in daily life.¹ But beyond the grogginess, irritability, and brain fog, chronic insomnia may actually contribute to structural changes in the brain—changes that could lead to cognitive decline and even dementia.³

Studies have shown that middle-aged adults (particularly those in their 50s and 60s) who report insomnia symptoms and regularly sleep less than six hours a night are at a significantly higher risk of developing cognitive impairment.⁴ In fact, they’re more than twice as likely to experience issues with memory, attention, and decision-making compared to those who get a healthy amount of rest.⁵ One large analysis even found that people who sleep less than six hours were 30% more likely to develop dementia down the line.⁴

So what’s going on in the brain when we skimp on sleep?

During healthy sleep, your brain performs a kind of overnight clean-up—clearing out toxic waste products, including beta amyloid, a protein known to accumulate in Alzheimer’s disease. But when sleep is shortened or fragmented, this clean-up process gets disrupted.⁶ Even a single night of sleep deprivation has been shown to increase levels of beta amyloid in the brain.⁶

Advanced brain imaging reveals even more cause for concern. People with chronic insomnia have been found to have reduced grey matter in key regions like the prefrontal cortex and hippocampus, areas critical for thinking, memory, and emotion regulation. White matter—the brain’s communication highways—also appears compromised.³

What’s especially striking is that the relationship may be bidirectional: insomnia can speed up cognitive decline, and cognitive decline can, in turn, make sleep worse.³ It’s a vicious cycle, and breaking it early is key.

With sleep playing such a foundational role in brain health, prioritising it isn’t just about feeling better—it’s about protecting your future.

Struggling to fall or stay asleep? Feeling foggy, forgetful, or less sharp than usual? It may be more than just a bad night’s sleep. If you regularly sleep less than six hours or experience symptoms of insomnia, speak with your doctor. Addressing sleep issues early could help protect your brain for years to come.

How Sove CPAP Clinic Can Help

Founded in 2008, Sove CPAP Clinic has grown to become a leading provider of respiratory and sleep services and products in Australia, with over 60 clinics nationwide. Our comprehensive clinical team includes Respiratory & Sleep Specialists, Sleep Technologists, and CPAP Consultants, ensuring that you receive comprehensive and personalised care. All medical procedures, including sleep studies and lung function testing, are bulk billed to all Australians, with minimal wait time.

If you would like to speak to a Respiratory & Sleep Physician, book a bulk-billed sleep study, or seek advice for your sleep apnea, you can reach us at 1300 76 29 39 or info@thecpapclinic.com.au.

ALWAYS FOLLOW THE DIRECTIONS FOR USE. CPAP is used for Obstructive Sleep Apnea treatment. When considering whether a sleep study or CPAP is right for you, speak to your doctor. Medicare criteria and T&Cs apply.

References

1. Fortier-Brochu, Émilie, and Charles M. Morin. “Cognitive Impairment in Individuals with Insomnia: Clinical Significance and Correlates.” Sleep, vol. 37, no. 11, 1 Nov. 2014, pp. 1787–1798, https://doi.org/10.5665/sleep.4172.
2. Godman, Heidi. “How Much Sleep Keeps Cognitive Decline at Bay?” Harvard Health, 1 Dec. 2021, www.health.harvard.edu/mind-and-mood/how-much-sleep-keeps-cognitive-decline-at-bay.
3. Zhang, Xiaotu, et al. “The Association between Insomnia and Cognitive Decline: A Scoping Review.” Sleep Medicine, vol. 124, 16 Oct. 2024, pp. 540–550, www.sciencedirect.com/science/article/pii/S1389945724004878, https://doi.org/10.1016/j.sleep.2024.10.021.
4. Bryant, Erin. “Lack of Sleep in Middle Age May Increase Dementia Risk.” National Institutes of Health (NIH), 27 Apr. 2021, www.nih.gov/news-events/nih-research-matters/lack-sleep-middle-age-may-increase-dementia-risk.
5. “Insomnia, Sleeping Less than Six Hours May Increase Risk of Cognitive Impairment | Penn State University.” Psu.edu, 2020, www.psu.edu/news/research/story/insomnia-sleeping-less-six-hours-may-increase-risk-cognitive-impairment. Accessed 20 June 2025.
6. Suni, Eric, and Nilong Vyas. “How Lack of Sleep Impacts Cognitive Performance and Focus.” Sleep Foundation, 18 July 2023, www.sleepfoundation.org/sleep-deprivation/lack-of-sleep-and-cognitive-impairment.