Caffeine is a stimulant that many people consume in the form of coffee for a quick energy boost. More than half of all Americans drink coffee every day, according to the February 2009 CBS News article "Caffeine Nation." Caffeine stimulates the central nervous system, increasing alertness, but it's a quick fix that sometimes leads to a "caffeine crash" or fatigue. Knowing how caffeine can cause fatigue will help you prevent energy crashes in your daily life.
Caffeine Overview
Caffeine stimulates the central nervous system and can make you feel more alert by fooling your brain into thinking it is not tired. In the brain, caffeine blocks adenosine, a chemical that promotes sleep, so your body may think it does not need rest when it is actually fatigued. Caffeine usually gives people an energy boost within 15 minutes of consuming it. Coffee contains about 95 to 200mg of caffeine per 8-oz. serving. The caffeine from coffee affects most people's nervous systems for about six hours.
Caffeine Crash
Caffeine can cause fatigue once the stimulant effects wear off. You may focus better and stay awake with caffeine in your system, but when the caffeine loses its power hours later, fatigue can hit. Once your body feels its natural tiredness without the caffeine's chemicals covering up tired sensations, you may feel drowsy and lethargic. Caffeine can also contribute to fatigue by allowing you to work longer and harder than your body normally would be able to while you're under the influence of the stimulant. Once the caffeine wears off, your body will feel fatigued.
Caffeine and Sleep
Caffeine can also make you feel fatigued by disrupting your sleep and can even trigger insomnia. Do not consume caffeine within six hours of your bedtime, the National Sleep Foundation advises, as it can keep you awake. Also, do not consume more than three 8-oz. cups of coffee or 250mg of caffeine per day. If you still experience sleep disturbances, cut caffeine out of your diet completely.
Considerations
People have different reactions to caffeine, with some people experiencing more negative side effects than others. If you do not normally drink caffeine, have a low body weight or are prone to anxiety, you are more likely to experience side effects such as nervousness or sleeplessness from caffeine. People who drink caffeine regularly often build up a tolerance to the drug, experiencing less side effects with small doses. The National Institutes of Health advise drinking no more than two to four cups of coffee a day to minimize your risk of negative side effects from caffeine.
