Caffeine is a drug, and it comes from the leaves, beans or nuts of different plants. It is a stimulant, meaning that it speeds up the brain and nervous system. Caffeine is most commonly found in coffee, tea, cocoa, chocolate, cola drinks, and energy drinks.

The Effects of Small and Large Amounts of Caffeine

Small amounts of caffeine are not harmful. The effect that caffeine has on you will depend on how much you consume, your height and weight, your general health, your mood, how often you have caffeine, and what you consume caffeine with. In small amounts, such as a single cup of coffee, the immediate effects of caffeine include making you feel more awake, making the heart beat faster, causing you to urinate more, raising the body temperature, and causing the digestive system to produce more acid. In large amounts, caffeine can cause headaches, make you feel restless, make you feel nervous, cause you to become delirious, and make it difficult for you to sleep.

In the long term, large amounts of caffeine can make it difficult for you to sleep, cause you to worry a lot, cause depression, and cause stomach upsets.

How Caffeine Affects your Hormones

Caffeine has effects on the physiology of your body. You feel the effects of it within a few minutes of consuming it and it stays in your system for four to six hours. Caffeine inhibits the absorption of adenosine, which calms the body, which makes you feel alert in the short run but can make it difficult to sleep. It injects adrenaline into your system, temporarily “revving you up” but this can cause fatigue and depression later. By taking more caffeine to counteract this, you will spend the day feeling agitated and may feel jumpy and edgy at night. It can increase the levels of cortisol, the body’s stress hormones, and this can lead to other health problems such as weight gain, moodiness, heart disease, and diabetes. Caffeine increases dopamine in the body, acting in a way similar to amphetamines, making you feel good when you take it but you feel down when it wears off.

Studies on Caffeine

Several studies have been conducted over the years to look at caffeine and its effect on health. These studies have dealt with the potential adverse effects of caffeine in areas such as:

• general toxicity
• cardiovascular effects
• effects of calcium balance and bone health
• behavioural effects in children and adults
• potential links to cancer
• effects on reproduction

These studies have been reviewed by scientists who have come to the following conclusions:

• adults are generally not at risk for adverse effects if they limit their intake of caffeine to 400mg-600mg per day
• people that get enough calcium in their daily diet have greater protection against the possible adverse effects of caffeine on bone health
• children are at increased risk for behavioural effects from caffeine compared to adults
• women of childbearing age are at increased risk of possible reproductive effects

Other Health Effects of Caffeine

Consuming caffeine before going to bed makes it harder to get to sleep, causes a shorter period of sleep, and lessens the amount of deep sleep that you have. Caffeine in limited amounts is safe during pregnancy but very large amounts can lead to miscarriage, stillbirth, or premature birth. If you are dependent on caffeine, you may find yourself experiencing withdrawal symptoms if you try to reduce your caffeine intake.