When I think of cold showers, I think of sexual frustration. It's something I've had to think of a lot in my sad, lonely life. The upside to an existence filled with dejection is that cold showers have many health benefits. And environmentally, cold showers are better than warm ones. Hot water is heated and, therefore, electricity is usually used. Plus, you're more likely to take a quick shower when you use cold water. So cold showers have several advantages to hot showers, except, of course, comfort.
Switching between cold and hot water in a shower can improve your circulation. When the shower is cold, all your blood goes to the organs to keep them heated. When the shower is hot, the blood goes to the skin to keep from overheating your organs. It's a way to get your blood flowing. And you'll be using half as much hot water.
NOTE: If you suffer from ill health, especially heart problems or are pregnant, consult a doctor before attempting this. The sudden burst of cold water can cause quite a shock.
Cold water is better for your complexion.
From Jasmin Malik Chua:
Hot water whisks away the water-retentive fatty substances in your skin, leaving it dry-or in serious cases, cracked, which can invite infection and inflammation.
People make all sorts of claims about the benefits of cold water on the noggin. They say it makes hair shinier and prevents baldness. I can't really find any science to back that up.
In theory, however, hot water opens pores, and cold water shrinks them or at least makes them less likely to expand.
Do what you want with that information.
Heat can affect your sperm count.
From Mayo Clinic:
To maximize the quality and quantity of your sperm, avoid hot tubs and baths. Spending more than 30 minutes in water 102 F (40 C) or above may lower your sperm count. Saunas and steam rooms may have a similar effect.