Why coffee makes you sleepy: the surprising science behind it

Many of us start the day with a cup of coffee. The dark brew stimulates and adds energy. It's due to caffeine, which stimulates and increases concentration. A cup of the drink helps focus on work or study. Sometimes, coffee has the opposite effect. It doesn't stimulate but rather makes you sleepy. Can coffee make you sleepy in a stimulating way? Why does coffee make you want to sleep?

You drink dark coffee and wait for it to stimulate you. It turns out that after a few minutes, you only feel more tired. You immediately want to sleep. Why does this happen? Caffeine should stimulate you. Where does the sleepiness after coffee come from?

Let's start with the basics. Coffee is a drink made from brewed and ground coffee beans. The dark drink hides many vitamins, such as B vitamins, which support the proper functioning of the nervous system. It's a legal stimulant that improves mood and helps with concentration.

This is all thanks to caffeine, which is classified as a psychoactive substance. It stimulates the nervous system and binds with adenosine, which helps control the sleep-wake cycle. It temporarily blocks its receptors, which causes sleepiness. However, this doesn't mean it completely stops adenosine production. For this reason, the stimulation after drinking coffee may only last for a short moment, and fatigue may quickly return with double the force.

When the level of caffeine in the body begins to decrease, adenosine takes its place, causing the brain to work at a slower pace. This is why you may feel sleepy and tired. Caffeine also increases the level of cortisol, the stress hormone. In this case, the effect is similar. Interestingly, the greater the body mass, the higher the possible concentration of cortisol in the blood. Therefore, people with extra weight are more prone to sleepiness after coffee.

Another reason could be how you tolerate sugar (it is absorbed faster than caffeine). Coffee with milk and sugar causes a major insulin spike. People with sugar metabolism disorders will feel stimulated only while drinking coffee, but soon after, they will feel very tired, sleepy, and completely drained. Headaches are also a normal reaction of the body in this case.

If you feel sleepy after coffee but can't give up the aromatic black coffee, change your habits. Do not exceed the recommended portion for daily consumption—2 cups. Also, say goodbye to additives like sugar, milk, or flavoured syrups, and the coffee will start working as it should. If you still don't feel well after drinking it, try green tea or the recently popular matcha, which has a stimulating and energising effect.