The body needs at least 4 hours to completely decompose coffee, so drinking in the evening is likely to cause shortness of breath, biological arrhythmia, insomnia.
A cup of 230 ml coffee has nearly 100 mg of caffeine. The US Food and Drug Administration (FDA) recommends adults to limit the amount of caffeine at 400 mg daily, equivalent to 4-5 cups.
Typically, the body takes about an hour to absorb 20% of coffee consumed. The ability to completely decompose coffee depends on the location of each person. People with the CYP1A2 gene help the body to decompose and eliminate caffeine quickly, usually takes about 2-3 hours to completely transform the caffeine, some cases are faster. People who do not carry this gene need about 4-12 hours to absorb all caffeine.
Other factors also affect the level of caffeine tolerance such as gender, drugs being used. Smokers who use more nicotine tend to metabolize caffeine faster. Pregnancy also slows the ability to eliminate caffeine.
Drinking coffee late at night can help those who work at night shifts, review the exam more awake. But restricting drinking in the afternoon or evening will be better because it can negatively affect sleep.
Disrupt sleep signal: Caffeine can prevent the brain from producing adenosine (chemicals that cause drowsiness). Adenosine acts as a nervous system inhibitor, slows brain activity to promote sleep and wake up at night. Adenosine gradually accumulated in the body all day to create a feeling of drowsiness, but when drinking coffee receptors, Adenosine receptors were blocked, making the drinker more awake at the end of the day.
Change the biological clock inside the body: Biological clock inside the body 24 hours of sleep – consciousness control. Drink a cup of coffee three hours before going to bed to deviate from the biological rhythm. Because caffeine changes hormones related to sleep, disturbing sleep, making sleep quality less.
Increase the feeling of anxiety and anxiety: Caffeine is a stimulant that affects the brain and nerves. The nervous system controls thinking and emotions (not to mention heart rate and breathing). For people who are easily worried, caffeine can make the symptoms worse, especially in the evening, increasing the risk of panic, nightmares. Drinking coffee at the end of the day can also cause unwanted effects such as restlessness or irritability in the evening.
In order for coffee not to affect sleep, adults should drink coffee before 16h, do not use more than 4 cups a day. Priority should be given to pure coffee or little sweet coffee, using unsweetened milk to avoid bad effects on health.