Caffeine, Fatigue & Sleepiness

While caffeine seems to provide a shot of energy during the mid-afternoon slump, the stimulant can make you more tired and fatigued. If you are sensitive to caffeine, you may experience its negative effects at small doses. Breaking the caffeine cycle can give you a better night's rest--making you more prepared to face the day.

How Caffeine Works

Caffeine makes you feel more alert by stimulating the central nervous system. The ingredient is a natural component of coffee, tea and chocolate, and it is an additive in soda and energy drinks. It causes your muscles to tense, your heart beat to increase and your blood vessels to open. In the mornings when you want to feel a jolt of energy, your coffee provides that punch. In the afternoon, when your body starts to feel sluggish, another dose of caffeine steps in to awaken your nervous system.

Fatigue

Also a symptom of caffeine withdrawal, fatigue occurs because your body induces a stress response when you consume caffeine. As the initial surge of energy provided by caffeine wears off, you may feel more tired than before you consumed it. Insomnia caused by caffeine can also make you feel more tired throughout the day. "U.S. Pharmacist" published an article in 2009 on fatigue and drowsiness. The study's author, W. Stephen Pray, told "Good Housekeeping" magazine that continuing to abuse caffeine causes fatigue in some patients. Increasing caffeine intake worsens fatigue.

Insomnia

Insomnia is one of the after-effects of taking caffeine close to bedtime or consuming too much of it during the day. Caffeine stops a nerve cell byproduct called adenosine from doing its job. Adenosine binds to neurons, slowing them down throughout the day. Eventually, the adenosine levels build up so much you become tired. When you consume caffeine, the stimulant takes the place of adenosine by attaching to neurons. Without enough adenosine built up in your body, you experience difficulty sleeping.

Recommended Limits

The Mayo Clinic notes 200 to 300mg of caffeine per day is harmless for most people. If you are more sensitive to caffeine, you can experience negative side effects with just one cup of coffee or tea. For others, consuming 500mg of caffeine or more can cause undesireable side effects, including insomnia, restlessness, upset stomach, increased heartbeat, nervousness, irritability and muscle tremors. Some antibiotics can increase and amplify caffeine's effects. A medication called theophylline produces effects similar to caffeine. Taking it with caffeine can increase the concentration of theophylline in your body. The herbal supplement echinacea can increase the concentration of caffeine and increase its side effects.