7/26/26: Is Benadryl Killing Your Brain 🧠?

www.karlsterling.comLong-term, regular use of diphenhydramine (Benadryl) as a sleep aid has real concerns for brain health:Anticholinergic burden and dementia risk — Several large studies (notably the 2015 JAMA Internal Medicine study) found a link between cumulative, long-term use of strong anticholinergic drugs like diphenhydramine and an increased risk of dementia, including Alzheimer's disease. The risk appeared dose- and duration-dependent.Impaired cognition — Diphenhydramine blocks acetylcholine, a neurotransmitter critical for memory and learning. Regular use is associated with brain fog, slower processing speed, and short-term memory problems.Tolerance to sedative effects — The drowsiness effect typically wears off within days to weeks of nightly use, so people often don't get quality sleep benefit anymore but keep taking it, meaning the anticholinergic exposure continues without the intended payoff.Disrupted sleep architecture — Even when it does sedate, it tends to suppress REM sleep, which plays a role in memory consolidation and emotional processing.Next-day grogginess ("hangover effect") — Its long half-life (especially in older adults) can cause lingering drowsiness, poor concentration, and slowed reaction time the following day.Increased fall and accident risk in older adults — Combines sedation with anticholinergic effects like dizziness and blurred vision, which is part of why it's on the Beers Criteria list of medications considered potentially inappropriate for older adults.Withdrawal/rebound insomnia — Stopping after chronic use can cause rebound insomnia, reinforcing a cycle of dependence on the drug to sleep at all.Confusion/delirium risk — Particularly in elderly patients, higher anticholinergic exposure is linked to acute confusion and delirium episodes.Worth noting: this research is largely observational/correlational, so it shows an association rather than definitively proven causation — but the consistency across studies has been enough that many clinicians now steer patients away from routine diphenhydramine use for sleep, especially older adults or those with any cognitive concerns.