Minute by minute What happens in your body after drinking the first cup of coffee?

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Morning coffee is an essential part of the daily routine for many, but have you ever wondered what exactly happens inside your body after drinking the first cup?

MailOnline has highlighted what happens in the body 'minute by minute' after drinking your morning coffee.

- Within the first ten minutes

The coffee takes effect just 10 minutes after the first sip.

Dr Duane Mellor, of the British Dietetic Association, says this reflects how quickly caffeine is absorbed into the bloodstream through parts of the digestive system.

He said: “After drinking coffee, caffeine will begin to appear in the blood after about 10 minutes. Some caffeine can be absorbed through the mouth and stomach, but in small quantities, as most absorption occurs in the first part of the intestine.”

People feel an increase in energy once they absorb the caffeine in coffee.

But caffeine doesn't actually provide energy. It prevents the body from interacting with adenosine, the chemical inside us that makes us feel tired, making us naturally more alert.

- After 20 minutes

Mellor explains that caffeine, which blocks adenosine receptors in the body, not only enhances alertness, but also causes blood pressure to rise within half an hour of drinking coffee, with the effect lasting for about 4 hours.

Caffeine causes blood vessels to constrict, thus increasing heart rate and high blood pressure.

The British National Health Service warns that drinking more than 4 cups of coffee a day may increase blood pressure in the long term.

- After 45 minutes

Mellor said caffeine's effects on the body peak after 45 minutes.

The stimulating effect of coffee, increases in heart rate and sense of energy, improves concentration and memory.

But drinking too much coffee may make you feel stressed and anxious.

NHS guidelines say around 400mg of caffeine per day is safe for adults, the equivalent of four regular cups.

- After 60 minutes

After the stimulating effect of caffeine kicks in, you may notice unwanted side effects.

Mellor says that once caffeine appears in the blood, its diuretic effect will begin.

Caffeine inhibits the production of antidiuretic hormone, or ADH, which normally helps regulate the amount of water in the body, according to the NHS. This causes the kidneys to not reabsorb water and increases the amount of urine.

A study conducted by the University of Birmingham's School of Sport and Exercise in 2014 found that there was no evidence of dehydration with moderate daily coffee consumption.

The NHS says drinking caffeine in moderation is a good way to stay hydrated.

Studies have also shown that coffee can activate colon and internal muscle contractions.

- After 90 minutes and beyond

The time it takes to metabolize caffeine varies from person to person. But for most people, the effects begin to wear off an hour or two after the first sip of coffee, along with the diuretic effects, according to Dr. Mellor.

This can cause feelings of fatigue, anxiety, and poor concentration.

Mellor explained: “For most people, the amount of caffeine decreases by about half after 6 hours, as it is metabolized by the liver. Although the effects may fade after an hour or two, caffeine remains in significant quantities in the body.”

Caffeine can stay in your body for up to 12 hours, according to researchers at the Sleep Foundation.

Many sleep experts recommend avoiding it at least 8 hours before bedtime.