David Letterman once said, "If it weren't for the coffee, I'd have no identifiable personality whatsoever."

Coffee helps improve concentration, keeps you alert, and gives an extra little boost in the morning. It might even help your personality become a bit more effervescent. But when it comes to your health, is coffee good or bad for you? Here are some things about coffee that you should know:

1. All coffee is not made equal. Each 16-ounce cup of java may have an incredibly different caffeine content, which is the main active ingredient. For example, a Starbucks coffee has 322 mg of caffeine, Wawa 251 mg, Dunkin Donuts 211 mg, and McDonald's 148 mg. Home brewed usually has even less. Even decaffeinated coffee has some caffeine, but usually only a couple of mg per cup.

2. Drinking coffee may help you live longer. The beneficial effects may be related to the non-caffeine ingredients in coffee called phenolic compounds. These compounds are antioxidants that may decrease inflammation and your risk of developing Type II diabetes.

3. Coffee is not bad for your heart. For many years, cardiologists thought that caffeine would increase the chance of developing an arrhythmia called atrial fibrillation, but new information suggests differently. A study published this year shows no increased risk in irregular heartbeat despite coffee intake. In fact, it may even be good for the ticker. A major study in 2014 concluded that a couple of cups of coffee a day may actually decrease your risk of having a heart attack or stroke.

4. Coffee can become addictive. According to the Food and Drug Administration, "when people use caffeine every day, their bodies get used to it, and they do not get the 'good effects' of feeling more awake and able to concentrate unless they use more of it." Withdrawal symptoms include headache, fatigue and becoming irritable if you miss your daily cup of Joe.

5. Coffee is not the only drink that has caffeine in it. According to the Center for Science in the Public Interest, a coke has 34 mg, diet coke 47 mg, tea 14-70 mg, and Mountain Dew has 54 mg caffeine in a 12 oz bottle, while chocolate contains 5-20 mg. The 5-hour energy drink has 200 mg of caffeine in it, and Red Bull has 80 mg in 8.4 ounces. This is less caffeine than a cup of coffee, and is more expensive.

6. Coffee can alter your sleep. Consuming caffeine within three to five hours before going to bed  can make it hard to fall asleep, and make you more likely to wake up during the night.

7. If you are having a problem with frequent urination, coffee may be playing a role. Cut back or eliminate it from your diet; it is a lot better to do this then to go on medication to treat frequent urination. Although it can act as a mild diuretic, moderate amounts should not make you dehydrated.

8. The ingredients that you add to your coffee may be bad for you. It is easy to take a fairly healthy drink and turn it into a caloric nightmare — sugar adds empty calories, while milk or cream adds saturated fats. A Starbucks Grande Caramel Frappuccino has 380 calories, and 18 grams of fat. A large coffee with cream and sugar from Dunkin Donuts has 260 calories.

So, is coffee good or bad for your health? The answer is probably a healthy combination of both. Coffee in moderation (up to 3 cups per day) may be good for you though I would not suggest drinking coffee medicinally for its health benefits. Then again, if you like it, there are worse habits to have.