One possibility is that you are hungry. After not eating all night, the body is ready for food. Some people are more sensitive to this than others. In your case, it might mean that you need to eat more promptly than others. You may want to try having breakfast or at least a snack right upon getting out of bed rather than waiting for your shower.
Another possibility is that you are having some pooling of blood in your feet. The tone in the blood vessels can be low in the mornings in some people. This means that, for example upon standing up, the blood may rush to your feet and this can make you feel dizzy. This would also explain the dizziness
that you feel after a hot shower. Again, the solution to this is to take it slowly in the mornings, avoiding rapid changes in position, and to make sure you stay well hydrated, as being dehydrated will accentuate this phenomenon.
On the whole, I do not think this is a problem that you need to worry
about. However, if it persists or worsens, if you find yourself passing out, or if you have any other new concerning symptoms you should talk to your primary care doctor