Which wakes you up more cold or hot water?

Cold water wakes you up more than hot water.

When you wake up in the morning, your body is still in a state of relaxed sleep, and your brain waves are slow and steady. When you take a cold shower, the cold water shocks your body and causes your brain waves to speed up, which leads to a more alert state of mind. This is why you feel more awake after taking a cold shower. In contrast, hot water does not have the same effect on the brain and does not jolt you out of sleep as effectively as cold water.