Cold exposure
Brief cold (cold shower, plunge) trains stress recovery. Don't overdo it.
Why
Brief, controlled cold exposure (a 60-second cold shower, a 2-3 minute plunge) elicits a sympathetic spike followed by enhanced parasympathetic rebound, training the nervous system's recovery response. Subjective mood improvements and reduced inflammation are reported. The hard evidence base is younger than the enthusiasm.
Slot in your day
How to do it
How
End your shower with 30–60 seconds cold, daily. Cold plunges 2–3 minutes, 1–3× per week. Always exit warm; don't overdo duration.
Ideal for
Stress-resilience training; not for cardiovascular exercise.
Sticking with it
End with cold rather than starting cold; the dread of starting cold derails consistency.
Markers this may influence
Evidence
Buijze 2016 PLOS ONE pragmatic RCT (n=3,018): a 30–90 s cold finish to the morning shower for 30 days cut self-reported sickness absence from work by 29% (IRR 0.71, p=0.003), but illness-days were unchanged, suggesting the effect is on perceived resilience more than infection rate. Hard outcomes remain limited; trial evidence is younger than the enthusiasm.