Coffee can be drunk at night, but it is not recommended. Coffee contains caffeine content, which generally has the effect of diuretic, dilating blood vessels and stimulating the nerve center. Drinking coffee at night may cause nerve excitation, affecting sleep time and sleep quality, and may lead to difficulty in falling asleep, waking up easily after sleep, and other symptoms of sleep disorders. Some people may experience abnormal symptoms such as headache and dizziness after drinking coffee, so it is not recommended to drink coffee 4 hours before going to bed at night. The best time to drink coffee is recommended to be around 9:00 a.m. and 2:00 p.m. Drinking coffee in the morning can ensure that the human body is full of energy, and has a good regulating effect on the phenomenon of dizziness and drowsiness caused after getting up. It can relieve physical fatigue, improve learning and work efficiency. It is recommended to drink coffee in moderation, but excessive consumption may affect the nervous system and digestive system.