I was taking cold showers before my ordeal started 5 years ago. This practice helped me not only with my sleep but with my mood as well. If I can't sleep at night taking a cold shower will relax me and made me fall asleep. In the morning is where it really does the trick. Mood improves, you feel more alive, and it last for several hours.
Not everybody stands the cold. You don't need that much really. Just a minute before finishing your shower will give benefits.
Phisically they improve your immune system and activates your lhinfatic system helping to detox.
If you can't stand it go slow. Control your breath. Soon you get use to it.
Mice