How does alcohol affect REM sleep?

Alcohol significantly affects REM sleep, which is the dream phase of sleep, often associated with memory consolidation. Matthew Walker, a neuroscientist and sleep researcher, addressed the potent blocking effect of alcohol on REM sleep during a discussion with Tim Ferriss. Alcohol produces metabolic byproducts such as acetaldehyde that demolish REM sleep, leading to memory retention issues. Walker shared a study demonstrating more than a 50% memory loss after individuals consumed alcohol on the first night following learning. Even drinking on the third night after learning negatively impacted memory retention, indicating that sleep continues to process and consolidate information days after learning 1.

Dr. Peter Attia, while conversing with Tim Ferriss, highlighted that alcohol consumption results not only in a significant reduction in REM sleep but also slightly reduces deep sleep and increases fragmentation, which worsens overall sleep quality. Even a single drink can cause some degradation of sleep 2.

Andrew Huberman also discussed alcohol as a toxin to the body and noted its pervasive negative effects, including the disruption of critical recovery processes and general health 3.

Excessive alcohol consumption, particularly in the context of sleep, is problematic because of its detrimental effect on REM sleep and can impair the body's natural cycles and memory processing functions.