In short, yes, cold showers are good for you. A cold shower’s a fight-or-flight scenario, meaning that if you tolerate it long enough, your body will release the hormone noradrenaline and activate the neurotransmitter acetylcholine, both of which are important to the sleep cycle.
Cold also stimulates endorphins, the happy hormones that help to improve your mood. A further study showed that it also reduced levels of inflammation markers – desirable for a swift recovery – via increasing cytokine levels in the blood. And there’s further mooted benefits of burning more fat and improving circulation.
So, all good, right? Possibly. Many of the studies involved cold-water immersion rather than cold-water showers, so you can’t directly equate one to the other.
Then again, a Dutch study involving 3,000 participants found those who finished their daily shower with a 30-90sec blast of cold water reported 29% fewer work-absence days than their colleagues.
For best results, build up to a 5-10min cold shower. Iceman Wim Hof (of the Wim Hof method) wisely recommends starting slowly, adding 30secs at the end of a hot shower until you reach this point. (That said, the ideal is arguably 100% cold showers, as hot water does dilute the potential benefits somewhat.)