Many people struggle to get a good night's sleep during midlife, including those raising young children, dealing with work-related stress and using technology more frequently throughout their lives. However, this might have more long-lasting effects than you think.
A recent study released in October 2024 showed that reduced brain volume, which is associated with normal aging and neurodegenerative conditions like dementia, is correlated with poor sleep in midlife and is apparent in brain scans even a decade later. Let's take a closer look at the study and why now is the time to prioritize getting better sleep for the sake of your future brain.
Poor sleep and brain aging
The study, published in Neurology, involved about 600 adults who averaged 40 years of age. They were questioned initially, followed by a follow-up questionnaire five years later and then a brain scan 10 years later after the follow-up. The correlation that emerged was based on machine learning's estimate of brain age based on changes in brain structure: when a person's brain was scanned, the machine could generate an estimate of brain age.
70% of participants reported no more than one poor sleep characteristic at the start of the study. Compared to this group, the folks who experienced moderate sleep challenges had brains that were, on average, 1.6 years older; the latter group constituted 22% of the sample. The 8% of people who reported having the most difficulty sleeping in midlife had brains that averaged 2.6 years older. The study shows a strong correlation, not causation, but these results emerge in an environment where sleep is being studied as a variable in brain health.
According to one of the authors, Clémence Cavaillès of the University of California in San Francisco Department of Psychiatry and Behavioral Sciences, "While we can't say that poor sleep causes dementia, earlier research has established an association. Even if the cause of dementia is unrelated to sleep, it's possible that poor sleep may advance or exacerbate cognitive symptoms."
It's also important to show that the issues that produced the correlation were difficulty getting to sleep, difficulty staying asleep and waking up too early, not overall amount of sleep. The correlation didn't emerge, for instance, just because someone slept less or more. The study suggests that sleep quality, rather than just total sleep duration, plays a significant role in brain health without ill effects.
Scientists continue to research whether improving sleep in midlife could help reduce risk factors for dementia and slow cognitive decline. Difficulty falling asleep and waking up too early are symptoms that may be worth your while to change, both because of the emerging research and because prioritizing good sleep can also improve your quality of life right now.
Role of sleep in brain health
Sleep has long been studied in association with how the brain works. Sleep plays a crucial role in memory consolidation, cognitive processing and learning. Chronic sleep disturbances have been associated with an increased risk of neurological conditions. Further research is needed to determine its direct impact on preventing neurodegeneration.
Research like this 2015 paper shows how sleep is a key time for the glymphatic system (the central nervous system's waste-clearing system) to perform rejuvenating work removing toxins from the central nervous system, and that sleep deprivation can impact its functioning.
A 2021 review found untreated obstructive sleep apnea is associated with a greater risk of cognitive decline and neurodegenerative diseases, including Alzheimer's disease and dementia. Further studies are needed to determine the extent of its role. Taken together, the research into the correlation between sleep and brain health suggests that addressing sleep disturbances in midlife may support long-term cognitive health.
Role of sleep in overall health
Getting enough high-quality sleep has been associated with improved immune function, reduced stress, faster recovery from illness and injury and a lower risk of chronic disease. In contrast, studies have shown that inadequate sleep is a risk factor for hypertension, type-2 diabetes, cardiovascular disease and impaired immune functioning.
Correlations also emerge when sleep and mental health are studied. A 2021 study of 273,695 US adults aged 18 to 64 found a correlation between inadequate sleep and frequent mental distress. As with other correlation-based studies, these two factors were shown to likely have a bidirectional relationship. Poor sleep can worsen mental health, and mental distress can disrupt sleep patterns. More research is needed to determine the extent of this interaction.
What counts as quality sleep?
According to the National Sleep Foundation and our medical reviewer, Annie Miller, licensed psychotherapist and sleep specialist, the markers of good sleep quality include:
- Being able to sleep at least six hours total per night.
- Being able to fall asleep within 30 minutes of going to bed.
- Sleeping through the night with minimal and brief awakenings.
- When sleep wakings happen, being able to get back to sleep within 20 minutes.
- Waking up in the morning feeling rested, as opposed to continuing to feel tired.
If multiple items on this list are hard for you to achieve, it might be time to work on improving your sleep.
Tips for getting quality sleep
When you get serious about getting better sleep, the next step is to start experimenting and seeing what factors in your life might help you sleep more. A great way to begin is by keeping a sleep diary and noting what changes you make to your sleep routine and how they improve or don't improve your sleep quality.
Other factors to consider if you want quality sleep:
- Food and drink impact sleep quality, but these reactions vary between individuals. Common culprits include caffeine, alcohol, large meals close to bedtime and highly processed or sugary foods. For instance, many people report challenges sleeping when they consume too much caffeine too late in the day, as well as difficulty sleeping when they consume alcohol. Tracking your consumption and adjusting it can help you see whether any food or drink impacts your sleep quality.
- Screen use and certain activities right before bed can also impact your sleep quality. "Screen use in bed impacts both children and adults by creating an association with being awake in bed. The content can also impact us," Miller explains. "Try to use screens out of bed and focus on more relaxing and less stimulating content."
- Besides screen use, you can manage your sleep environment by ensuring your space is dark and cool, that your sleep surface is comfortable and not contributing to pain and that other sensory needs are met, such as sleeping with white noise or an eye mask.
- Other frequently cited beneficial habits for higher sleep quality include regular exercise and a consistent sleep schedule. Miller adds that if you struggle to fall asleep, try waiting until you feel sleepy rather than forcing sleep, which can increase frustration and insomnia.
- If you feel stress is a major contributor to your sleep quality issues, it's worth it to try a new routine specifically to address nighttime anxiety or stress. Miller states that giving yourself 1-2 hours of wind-down time to relax (not work, etc) before bed is an important step. Making bedtime a calming, positive experience can take time, but working on that routine may yield results.
Be aware that sleep quality and susceptibility to sleep disorders have a genetic component, but lifestyle and environmental factors also play a major role in sleep health. While it's a great idea to try lifestyle changes to work toward more quality sleep, if they do not work for you, talking to a medical professional or behavioral sleep therapist. A sleep study may be recommended to assess for disorders like sleep apnea, according to Miller. Evidence-based treatments — such as cognitive behavioral therapy for insomnia (CBT-i) — may be considered.
When to see a doctor for poor sleep
If you've tried making lifestyle changes but still struggle with poor sleep, talking to a doctor can help identify underlying causes and explore additional treatment options. You can bring your sleep diary and what you've learned about your sleep to get an informed opinion on the next steps.
If lifestyle changes — including optimizing your sleep environment, diet and stress management — have not improved your sleep, a healthcare provider may explore additional evaluations. Evidence-based treatments such as cognitive behavioral therapy for insomnia (CBT-i) are considered the first-line treatment for insomnia.
The bottom line
While evidence is emerging that poor sleep quality may be linked to accelerated brain aging, the underlying causes of dementia remain complex and under investigation. However, improving sleep quality by optimizing your sleep environment, addressing stress and using evidence-based strategies can have immediate benefits. You might also be protecting your brain for the next few decades simultaneously.
English (US) ·