Lots of people drink a cup or two of coffee per day without even thinking about how it will affect their sleep and instead using it as a fast-acting stimulant to keep them energized throughout the day. It can increase your blood pressure, heart rate and give you more energy, but there are a few different side-effects of using caffeine in this manner, such as trouble falling asleep at night or feeling anxious.
There are a few different studies that show coffee is good to drink, including one study in Europe that found drinking coffee can lower one's morality and another that coffee can extend lifespans for non-white people of various races. A separate 2017 study found that drinking 3-4 cups of coffee a day can reduce your chance of getting serious diseases like cancer.
Though caffeine might seem like a drug due to the fast-acting nature of it, there's not much similarities between the two besides their ability to block sleep. Drinking coffee makes you more awake and in some cases can make it more difficult to go to sleep at night if consumed around bedtime. People who smoke usually need to drink more caffeine to get the same amount of stimulation as someone who doesn't smoke, which can make things worse if you tend to do both hand-in-hand.
Caffeine's half-life — the amount of time it takes for half the substance to be removed from the body — is between 5-6 hours and is still in your system after that, but has a diminishing impact on the body. This is only an average, so for some people it could be in their bodies after a whole afternoon, but for someone else it could leave their body within a couple hours. There's many reasons why coffee might stay in one person's body longer than other: things like weight, gender and ethnicity all make an impact. Enzymes are what process and break down caffeine, but when they are dealing with things like drugs, antidepressants, oral pregnancy pills and even Tylenol can slow the process down.
Half-life of coffee in the average adult
Though it might be hard to avoid caffeine due to the amount of foods and beverages it can be found in, it's best to avoid black and green teas, coffee, chocolate, energy drinks, soft drinks and some over the counter medications before you go to bed. Even decaffeinated coffee has small amounts of the substance in it, so it's best to avoid that too if you're overly sensitive to caffeine.
Drinking caffeinated beverages before bed is never a good idea because it disrupts your rapid eye movement (REM) sleep when your body processes your emotions and the events that happened throughout the day. If coffee interrupts this, you'll wake up the next day feeling odd, groggy or even sad or mad and will likely grab a cup of coffee to shake the feeling.
Coffee drinkers can also try numerous other tips to lessen their dependence on caffeine, including drinking water more often, getting between 7-8 hours of sleep per night, avoiding naps and overly processed foods and exercising daily to tire yourself before bed.