Are you properly hydrated?
Proper hydration is a huge concern for divers because of its connection to Decompression Illness. Its tough enough to stay properly hydrated in the summer heat, but add to that ingestion of diuretic substances such as coffee and sodas, and you have a bad recipe for health. You should drink half your weight in ounces of water each day and that does not include diuretic drinks. That means a 200 pound man should drink 100 ounces of water. Most of us get dehydrated over a long period of time, so you can't necessarily catch up on the morning of a dive. Drinks lots, pee clear and you should have a healthier, more alert dive.