Caffeine helps you stay awake and alert because it is a central nervous system stimulant. In fact, you may feel the effects from caffeine for up to 6 hours. This drug stimulates your central nervous system, in part, by affecting certain neurotransmitters in your body such as norepinephrine. Caffeine is found in food, beverages like coffee, over-the-counter drugs and prescription medication. Consult a doctor before adding caffeine to your diet or using it medicinally.
Significance
Caffeine amplifies the effects of norepinephrine, a neurotransmitter, in your body. Norepinephrine is important for attentiveness, learning, emotions, sleeping and dreaming. It is also released as a hormone into your blood that causes your heart rate to increase and your blood vessels to contract.
Effects
Caffeine's ability to boost norepinephrine helps explain why it can cause anxiety, insomnia and jitters. High levels of this excitatory neurotransmitter are linked to stress, anxiety and hyperactivity. Low levels, meanwhile, are linked to lack of focus and energy, according to the Canadian Institutes of Health.
Heart Considerations
Caffeine can worsen some heart problems because it causes norepinephrine and epinephrine to increase the force and rate of heart contractions. This increases your blood pressure and delivers more oxygen throughout your body. These neurotransmitters act in concert but are released from different areas. Norepinephrine, also called noradrenaline, comes from the sympathetic nerves near your heart's pacemaker tissue. Epinephrine, also called adrenaline, is released mainly by your adrenal glands. Together, these neurotransmitters cause "fight or flight" behavior.
Physiology
Caffeine appears to work by antagonizing, or blocking, your adenosine receptors, which promotes neurotransmitter release. This chain of events leads to the stimulatory effects of caffeine.
References
- KidsHealth.org; What is Caffeine?; 2011
- Scientific American; How Does Caffeine Affect the Body?; February 1999
- Elmhurst College: Central Nervous System; 2003
- The Brain; The Brain From Top To Bottom; Bruno Dubuc; 2002
- "Journal of Cardiovascular Pharmacology"; Central Effects of Caffeine on Renal Renin Secretion and Norepinephrine Spillover; S.P. Tofovic, et al; August 1996
- Integrative Psychiatry; The Four Major Neurotransmitters; 2011
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