Coffee and tea contain caffeine. Cigarette smoke and sugar candy contain nicotine, which is not beneficial for sleep. Some medications, such as drugs for treating nasal congestion, asthma and heart problems, will make nerves more stimulated, which is also not beneficial for sleep.
There are many types of coffee on the market and their caffeine content is also different. For example, for a 360ml cup of coffee, the caffeine content of some popular coffees such as 336 mg cold brewed coffee, 260 mg machine brewed coffee, American 150 mg...
However, the amount of caffeine in a cup of coffee varies depending on the type of coffee beans, the origin, the level of roasting, the method and the time of making the coffee.
The half-life of caffeine (the time it takes for the body to reduce its content to half) varies from person to person. For adults, the average time is 3-7 hours, while for pregnant women, the half-time can be twice as long as the average for adults.
Therefore, if you plan to go to bed at 10pm, it is best to drink coffee before 4pm (for normal people without sleep disorders).
