Why does the shower wake you up, no matter how tired you are?

Question:

There have been days when I didn't get much sleep, but I had to wake up. So I took a shower, and voila, I was awake. Why does this happen?

Answers:
I'm not sure if it's the sound of the water, the smell of soap and shampoo or the invigorating water hitting my head, shoulders and back that gets my circulation pumping.
The saying of washing away your troubles is true as the dead skin gets sluffed off and the perspiration/dirt falls down the drain.
I don't know what I'd do if I had to miss my weekday shower to wake up and start the day.

The pressure is relaxing, water refreshing and, I am assuming hot.Once you step out into the air, you are cooled down.There is nothing better than a refreshing shower no matter how awake or tired you are!

Why does the shower wake you up, no matter how tired you are?

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