The Core Issue

Sleep and gut bacteria are both known to affect health in older adults, but nobody had pinned down a specific bacterial species tied to actual insomnia symptoms using both self-reports and wearable data in the same study.

The Finding

Researchers followed 869 older adults (average age 70.7) in a long-running aging cohort, checking self-reported sleep, actigraphy (wearable sleep trackers) in a subset, and full gut bacteria DNA sequencing. People with frequent trouble falling asleep and excessive daytime sleepiness both showed lower levels of one bacterium, Eubacterium sp. CAG:251. People with better device-measured sleep efficiency were roughly twice as likely to have it present.

Why It Matters

This is one of the more specific gut-sleep links to come out of a real human cohort instead of mice. It doesn't prove cause and effect, but it gives researchers an actual bacterial target to chase in future studies on insomnia and aging.

Limitations of Study

This is a single snapshot in time (cross-sectional), so it can't say whether poor sleep drains this bacterium or the missing bacterium worsens sleep. The researchers call it exploratory and want it repeated over time before drawing conclusions. Self-reported sleep and the wearable device data didn't line up with each other especially well either.

Interesting Statistics

\- 869 older adults studied, 332 of them also wore sleep-tracking devices  
\- People with frequent trouble falling asleep had about 0.41 standard deviations higher bacterial diversity, not lower  
\- Better sleep efficiency roughly doubled the odds of having this bacterium present

TL;DR

A study of 869 older adults found insomnia and daytime sleepiness consistently line up with depleted levels of one specific gut bacterium, but it's early and exploratory, not proof of cause and effect.

Full article: https://biomesci.com/gut-bacterium-eubacterium-cag251-insomnia-older-adults-2/

Scientists find one gut bacterium that's consistently missing in older adults with insomnia