We know sleep is crucial for our health, but with work, family, and social events competing for time, it’s common to put off bedtime by an hour or two. We may think missing a little sleep doesn’t make a big difference in our overall well-being. However, two new studies suggest that over time, even small amounts of sleep deprivation can have significant health effects on our hearts and brains.

The first study explored how mild sleep restriction affects the risk of heart disease. Previous research has suggested that losing sleep may harm cardiovascular systems, but the new study is notable for two reasons: First, it demonstrates how even a small amount of sleep loss affects our health. Second, it zeros in on how sleep deprivation can specifically impact cardiovascular health

The experiment included 35 women aged 18 and older who typically sleep 7-9 hours per night. Over six weeks, one group slept their usual amount, while the other restricted their sleep by going to bed an hour and a half later each night. Researchers then sampled and studied cells from the lining of their blood vessels. 

When the people in the study didn’t get enough sleep, the body produced more free radicals — molecules that can damage cells. Usually, the cells that line blood vessels protect themselves by producing antioxidants to neutralize these free radicals. But the study found that even an hour and a half of missed sleep weakens these cells, so they don’t produce enough antioxidants to counter the excess free radicals from sleep deprivation. Results suggest that over time this can raise the risk of cardiovascular disease. 

The second study adds a new understanding of how sleep deprivation may affect the brain over time. Specifically, it examined how even a slight decrease in deep sleep, also known as slow-wave sleep (SWS), may increase the risk of dementia.   

Researchers analyzed data from 346 participants aged 60 and older who took part in two sleep studies five years apart between 1995 and 2001. Participants showed no signs of dementia at the time of the second sleep study. They were subsequently followed until 2018 for the development of dementia. The researchers completed their data analysis in August 2023. 

The results between the first and second sleep study showed a decline in SWS as participants aged. In addition, over 17 years of follow-up, 52 participants developed dementia. After analyzing the data, the researchers concluded that every 1% per year loss of SWS was associated with a 27% higher dementia risk. 

Scientists have noticed a correlation between sleep deprivation and dementia for years. This study helps explain that losing out on the deepest part of sleep in small amounts can significantly raise the risk of dementia. While some dementia risk factors like genetics are not controllable, avoiding sleep deprivation is a concrete action seniors can take to reduce their risk. 

Taken together, both studies help explain why sleep is vital to our mental and physical health. No matter how tempted you are to stay up that extra hour, your time is better spent getting a good night’s sleep.

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4 Sources

  1. Shah, R., Shah, V.K., Emin, M. et al. Mild sleep restriction increases endothelial oxidative stress in female persons. Sci Rep 13, 15360 (2023).

  2. Makarem, N., Castro‐Diehl, C., St‐Onge, M., Redline, S., Shea, S., Lloyd‐Jones, D. M., Ning, H., & Aggarwal, B. (2022). Redefining cardiovascular health to include sleep: Prospective Associations with Cardiovascular Disease in the MESA Sleep Study. Journal of the American Heart Association, 11(21).

  3. Himali, J. J., Baril, A., Cavuoto, M. G., Yiallourou, S., Wiedner, C. D., Himali, D., DeCarli, C., Redline, S., Beiser, A. S., Seshadri, S., & Pase, M. P. (2023). Association between Slow-Wave sleep loss and incident dementia. JAMA Neurology.

  4. Does poor sleep raise risk for Alzheimer’s disease? (2016, February 29). National Institute on Aging.


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