It is a stimulant and this is why most people have coffee in the morning to aid in the waking up process. Of course coffee is not intended to replace sleep, but only to make us a little more alert.
The effect takes about 15 minutes and it takes about 6 hours for your body to reduce the caffeine by half.
Three cups is considered a moderate amount, but 8 is highly excessive. And just before bed is not recommended.
Caffeine in moderate doses can cause insomnia or headaches, nervousness and dizziness. Drinking coffee moderately can also trigger anxiety, excessive urination and sleep disturbance.
It is important to know the caffeine content of your food and drinks so you can have a good night’s sleep.
Foods high in caffeine include: beverages, baked products, breakfast cereals and sweets.