There's a real mechanism behind part of this idea — heat trapped by tight underwear affects male fertility — but stretching it into a universal "anti-aging" habit (circulation, inflammation, skin barrier, hormones, deep sleep, for everyone) goes well beyond what the research shows.

noli's read

Stripped of its framing ("the most underrated anti-aging habit"), the claim rests on a real but narrowly defined kernel of truth: scrotal thermoregulation is a documented factor in male sperm quality. A literature review and a cross-sectional study of over 650 men found that loose-fitting underwear (boxers) is associated with 20-25% higher sperm concentration than tight underwear, via roughly 1°C lower scrotal temperature. That's solid, but specific to men and to fertility — nothing in that literature documents an effect on general circulation, systemic inflammation, skin barrier function, overall hormone balance, or sleep depth, for men or women. The post generalizes a real but narrow mechanism (testicular temperature and spermatogenesis) into an unsourced list of "anti-aging" benefits, which clearly overstates what the available data shows.

the sources

1. 1Garolla A, Torino M, Sartini B, et al. 2013
2. 2Gundersen TD, Jørgensen N, Andersson AM, et al. 2015