Many people drink a steaming cup or mug of coffee first thing in the morning to really wake them up. Others rely on coffee to help them stay awake during the afternoon slump at work. If you’re one of those people who simply cannot function properly without their morning and afternoon cup of joe, you should know that it doesn’t always “work” and you end up feeling sluggish instead of energized.
There are times when drinking coffee can make you feel tired and sleepy, for which you may think you just have a high tolerance for caffeine. That is indeed one of the reasons, but there’s more to it than that. Here’s a look at how and why drinking coffee can make you drowsy and fatigued.
What caffeine does
The caffeine in coffee is a nervous system stimulant. It signals the release of hormones in the body that can increase blood pressure and heart rate. The boost in cardiovascular activity brings more oxygenated blood to the body’s tissues, causing coffee drinkers to feel more alert, awake, and energized.
Caffeine also blocks receptors in the brain from receiving a neurotransmitter called adenosine, which causes fatigue. However, the body still continues to produce adenosine, which builds up until the caffeine wears off and the neurotransmitter gets access to the brain again, making you sleepy. This means that all caffeine does is delay the effects of adenosine and cover up drowsiness.
Coffee and dehydration
Coffee is a diuretic that makes you need to urinate. Consuming coffee to get out of an afternoon slump can result in a cycle of dehydration that would actually make you feel more tired. What happens is that after drinking coffee, you would experience an initial burst of energy but would also need to go to the bathroom to pass water. As a result of water loss, your blood thickens, making it move more slowly through your blood vessels.
Coffee is also a vasoconstrictor, which means it makes your blood vessels (the arteries and veins) narrower, making it more difficult for blood to be transported to the different parts of the body.
Because of the slow movement of blood, less oxygen is delivered throughout the body. And with oxygen deprivation, you feel sleepy. At this point you may be thinking the effects of caffeine have worn off, so you may be inclined to make yourself another cup to fight off sleep, repeating the cycle. Plus, when you drink coffee, you probably don’t think of drinking water too, or even if you do drink water, the amount of water you take in isn’t enough to fully rehydrate your body.
Sugar in your coffee
If you like your coffee sweet, you may have experienced a sugar crash soon after emptying your cup. The body processes sugar faster than coffee, so you’re left without energy after it’s used up. With coffee-flavored drinks that are high in sugar but low in actual caffeine content, you may have a sugar rush and crash, not really a caffeine boost.
How to prevent sleepiness when drinking coffee
It’s recommended to stay hydrated when drinking coffee, or any caffeinated product. Each time you drink a cup of coffee, drink a glass of water too. You can also cut down on the sugar to avoid crashing and feeling sleepy afterward.