How some caffeine can be beneficial and too much can be harmful.
VIDEO TRANSCRIPT
Need a coffee jolt to start your day?
This wake-up call is courtesy of caffeine, a stimulant also found in tea, soda, and energy drinks, that increases activity in your brain and nervous system.
Caffeine does this by blocking receptors in the brain for a chemical called adenosine which turns down the central nervous system so you can fall asleep.
Without adenosine, the brain keeps you awake and alert. Caffeine also increases levels of the hormones cortisol and adrenaline, which make your heart pump faster and speed up your breathing.
Because the body absorbs caffeine quickly, its effects typically kick in within 10 or 15 minutes.
Caffeine can improve memory and concentration, which may help at work. It can also boost your mood and even enhance athletic performance.
But too much caffeine can make you jittery and cause other unwanted side effects including headaches, upset stomach, irritability, and anxiety.
It can also interfere with sleep even if consumed as much as six hours before bed. That’s why it’s a good idea to avoid caffeine in the late afternoon and evening.
During pregnancy, caffeine may increase the risk for miscarriage and low birth weight.
So how much caffeine is safe for adults? Experts say 400 milligrams a day. That’s roughly the amount in 4 eight-ounce cups of coffee, though some types of coffee contain more.
During pregnancy, limit caffeine to 200 milligrams a day.
Keep in mind that different sources have different amounts of caffeine.
Those little energy shots can pack 200 milligrams or more while soda, tea, and chocolate typically contain less caffeine than regular coffee.
Caffeine’s effects vary from person to person.
Those who don’t consume much tend to be more sensitive to it.
But heavy users can build up a tolerance, which means the more you consume, the more caffeine you may need to get that quick pick-me-up.