I found some good information on the official Nivea website, so I brought it here.
______
About 70% of women enjoy warm showers. Only the remaining 30% dare to alternate between hot and cold water. Doing so promotes circulation and strengthens the immune system. It is a beauty secret for firm skin and a radiant complexion!
Alternating between cold and hot water can help you wake up completely. It aids in muscle regeneration, making it suitable even after a strenuous workout. Taking a shower this way in the evening relaxes your body, and you can fall asleep easily, especially if you finish by rinsing with cold water and wrapping yourself in warmth.
______
I fall into the 70% category lol
Taking a cold shower isn't easy, but since it's said to be good for the health, I think I'll give it a try.
(Information source: Nivea official website)