Substances use and abuse. Caffeine.
Teens and young adults like to push boundaries. They take risks. Some take bigger risks than others, and the types of risks vary. Alcohol is often abused, as is caffeine, by college students. Both decrease sleep quality. 8 hours of sleep many only be as restful as 6 hours after drinking alcohol or caffeine.
I am seeing an increase in caffeine abuse. The promotion of energy drinks among college students definitely work. In fact, there's a Red Bull car that drives around downtown. Admittedly, it's a pretty cool-looking car with a giant can of Red Bull on the roof.
In my opinion, occasional caffeine intake (a few times a week, in small quantities) is fine. So eating a chocolate cake, drinking a cappuccino with friends, having a cup of tea while studying for a test in the afternoon are all fine ways to enjoy and use caffeine. Someone who has a cup of coffee every morning is probably chemically dependent on that drug. Someone who uses coffee to fend off the effects of alcohol has a serious problem with both substances. If you can't stop drinking daily coffees without getting a headache, you know your body's dependent. If you use caffeine to get high and act crazy to impress friends, you're abusing it.
I've seen students jittery and shaky, not knowing what's going on with their body from ingesting too much caffeine in the form of energy drinks and caffeine pills. One student ended up missing the test she was up all night studying for because she was having severe physical effects.
The slightly older and highly-stressed graduate students develop high blood pressure through their indentured schooling. They don't have as many problems with alcohol, but they certainly love their caffeine. Most hang out at the coffee shops downtown all day long during dissertation writing. Despite a family history of high blood pressure, heart disease, and diabetes, and a steady trend to developing those diseases themselves, the grad students ignore their health in favor of a chemically-induced zombie-like constantly-wired state of being. What they don't realize is that when they stay up late trying to get an experiment done, they are probably making mistakes and will have to repeat the experiment again anyway when they are alert. It's hard to make the right decisions when tired, no matter how much caffeine is in the brain. (Trust me. Been there; done that.)
Caffeine as a drug is underrated. Abusing it is not as shameful as alcohol, and in some circles, is even promoted. Yet, it has harmful effects like high blood pressure, palpitations (racing heart beats), and insomnia. Addiction rates are high. If someone is concerned about sleep quality, caffeine use must be minimized.