brain fog

noun

: a usually temporary state of diminished mental capacity marked by inability to concentrate or to think or reason clearly

Examples of brain fog in a Sentence

Recent Examples on the Web

The disconnect matters because women in their 30s and early 40s may not realize that mood changes, sleep disruption and brain fog can be tied to hormonal shifts. — Hanna Wickes, Sacbee.com, 25 July 2026

Riding a national surge of interest in treatments for menopause, the affiliate also began offering specialized care for women in perimenopause, a period before menopause begins that can bring insomnia and brain fog. — Grant Stringer, Mercury News, 21 July 2026

Some of the most common include irregular periods, hot flashes, night sweats, sleep disturbances, mood changes, vaginal dryness, brain fog and joint pain as hormone levels begin to fluctuate, according to Mayo Clinic. — Melissa Rudy, FOXNews.com, 21 July 2026

Competing demands — for example, from illness, injury, or chronic stress — can appear not only as poor health, but also as negative conscious experiences such as anxiety, brain fog, and exhaustion. — Rachel Nuwer, Quanta Magazine, 17 July 2026

Word History

First Known Use

1853, in the meaning defined above

Rhymes for brain fog

• agog
• backlog
• bulldog
• bullfrog
• eclogue
• eggnog
• groundhog
• hedgehog
• leapfrog
• prolog
• sheepdog
• watchdog

Medical Definition

brain fog

noun

: a usually temporary state of diminished mental capacity marked by inability to concentrate or to think or reason clearly

This brain fog can be a result of being overly stressed, tired, carrying extra weight, consuming too many calories or consistently consuming a diet poor in nutrients.

—Kylie Helgens, The Gazette (Cedar Rapids, Iowa)