Most American adults have consumed caffeine; as one of the most commonly used drugs in the world, it's used regularly by an estimated 90 percent of people in the world, says Brown University Health Services. You've probably downed a cup of coffee to wake yourself up and stay alert at one time or another, perhaps even daily. But when it comes to afternoon sleepiness, caffeine can be helpful or harmful, depending on your circumstances.
What is Caffeine?
Caffeine is a central nervous system stimulant. It exists naturally in numerous plants, and is generally consumed via coffee, tea, soda and chocolate -- although it can also be included in energy drinks, sports drinks and over-the-counter pain medications. According to the University of Utah College of Pharmacy, caffeine is the only stimulant drug that is classified as safe and effective by the Food and Drug Administration.
Caffeine's Effects
As a central nervous system stimulant, caffeine makes you feel more awake and alert; however, it also has a number of other effects on your body. Caffeine speeds up your heart rate, raises your blood pressure, increases your brain's production of dopamine -- which elevates mood -- and can sometimes cause insomnia, anxious feelings, "the jitters," nausea or headache, if consumed in excess, says Brown University Health Services.
Daytime Fatigue
Because caffeine increases wakefulness, many people use it to feel more rested and alert during an afternoon "slump," perhaps taking a coffee break to revive themselves before resuming normal tasks. Brown University notes that caffeine's effects are felt the strongest approximately one hour after consumption; therefore, ingesting some caffeine in the early to mid-afternoon to combat afternoon sleepiness will likely make you feel more awake. The Dartmouth Undergraduate Journal of Science reports that combining a dose of caffeine with a short nap -- 15 to 20 minutes at most -- can result in an even more pronounced wakefulness effect.
Caveats
There is a downside to using caffeine to alleviate afternoon sleepiness, however. Caffeine remains in your body for several hours; therefore, ingesting caffeine in the afternoon to wake yourself up can cause sleep difficulties that night, says MayoClinic.com. This can set you up in a troublesome cycle, where you obtain inadequate amounts of sleep at night due to difficulty falling asleep, then consume caffeine to stay awake during the day. In addition, while 200 to 300 mg of caffeine per day is typically considered safe according to MayoClinic.com, large amounts of caffeine can cause adverse side effects such as a racing heart and restlessness. If you have concerns about your caffeine intake or sleep patterns, consult your physician for evaluation and medical advice.
References
- Brown University Health Services; Caffeine
- MayoClinic.com; Caffeine (Oral Route, Parenteral Route); November 2010
- University of Utah College of Pharmacy; Caffeine
- Dartmouth Undergraduate Journal of Science; Caffeine and Naps: The Fight Against Sleep Deprivation; Kyel Heppenstal; February 2011
- MayoClinic.com; Caffeine: How Much is Too Much?; March 2011
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