Let me start out by saying that I have many detractors regarding this topic. Coffee and wine drinkers hate this argument and fight tooth and nail to protect their use. Here's how I feel about both.
First off, caffeine and alcohol are both considered (by many experts) slow poisons that over time can cause many health issues down the line. Both form an acidic environment in the body which can lead to heart disease, inflammation, arthritis, diabetes and major digestive issues.
Both wreak havoc on your blood sugar and how it's regulated. Caffeine taxes the adrenal glands which are responsible for regulating your hormones. It puts the body into a fight or flight mode (all the time) which can cause longterm ill-health effects and difficulty with weight loss. It also stimulates our central nervous system which can affect perception, moods and behavior. Although it does increase the "feel-good" neurotransmitter dopamine when we drink it, over time you need more and more caffeine for the desired effect.
Dropping these two "toxins" will help you find your natural energy without a dependence on anything outside of food to get energy or relax. Removing both will help you to have deeper and more restful sleep.
When we drink alcohol we rarely go into REM sleep, which means our bodies don't get the healing recovery rest that we need. Over time, it also depletes serotonin in our bodies, which can then cause depression, mood swings and other issues related to low serotonin. Drinking also affects our neurotransmitters in our brain, thinking patterns, memory and hormone regulation. Not to mention what it does to the liver...I think you probably know that already!