Sleeping too long increases biomarkers for neurological disorders

Poor sleep affects many physiological aspects, so it's no surprise that scientists have found a potential link between sleep patterns and neurological diseases.

Sleep disturbances are a common problem worldwide. When our sleep quality is poor, it significantly impacts our daily life.

We’ve all experienced those sleepless nights, tossing and turning for various reasons, and we can feel the effects of sleep deprivation—or even oversleeping—on our bodies and minds the next day.

But those nights may impact your brain health in the long run ...

The study
The researchers analyzed data from a large U.S. National Health and Nutrition Examination Survey conducted in 2013-14 on American adults.

They compared information on participants' sleep patterns with the levels of a specific neurofilament light chain, a biomarker found in their blood samples.

This particular biomarker is known to increase in both cerebrospinal fluid (the fluid surrounding the brain) and blood in proportion to the extent of brain cell damage. Elevated levels of this biomarker are seen in a range of neurological disorders, including some of the most severe: Alzheimer's disease, frontotemporal dementia, multiple sclerosis, traumatic brain injury, and cerebrovascular diseases.

The study included 1,637 participants, with an equal number of men and women. They reported their sleep quality as either healthy, moderate, or poor, and indicated whether they already had a diagnosed sleep disorder.

Participants also reported their sleep duration: a little over one-third slept 6 hours or less per night, half slept 7-8 hours, and about 7% slept 9 hours or more.

The findings showed that individuals with longer sleep durations, poor sleep patterns, or a diagnosed sleep disorder had higher levels of the biomarker for neurological diseases. However, a significant elevation was only observed in one group: those who slept more than 9 hours per night. That’s a surprising result.

It would be interesting if the scientists conducted a follow-up with the same participants in 5-10 years to see how many actually developed a neurological disease. If the link between excessive sleep and the biomarker is as strong as the connection between excessive sleep and disease - that would be a real game changer.

In conclusion, longer sleep duration at night is associated with higher levels of biomarkers linked to brain diseases. 

We can all agree that good-quality sleep is crucial. The new insight here is that this may not only apply to the immediate discomfort we feel after a poor night’s sleep; our sleep patterns and duration might also influence the risk of developing brain-related diseases.

Sleep tight (but not too long?).

About the scientific paper:

First Authors: Chunyan Zhang + Yitian Yang, China
Published: BMC Public Health, October 2024.
Link to paper: https://bmcpublichealth.biomedcentral.com/articles/10.1186/s12889-024-20184-7