For many of us, we drink coffee as our kickstarter for the day, but have you ever felt tired and sleepy after drinking coffee?

Well, there is an explanation behind that, for some coffee lovers they can drink three or more cups of coffee a day without feeling jittery and gives them ample of energy, but for some, they will feel tired and sleepy after a cup of Joe.

1. Sometimes the caffeine is not working in our body and doesn’t give us alertness we needed this is because of the coffee blocks our adenosines. Adenosines is a chemical in the central nervous system that regulates the sleep-wake cycle. When you’re awake during the day, your adenosine levels increase, eventually making you drowsy by suppressing the activity of cells in the basal forebrain. After you fall asleep, adenosine levels drop.

The caffeine in coffee blocks the brains adenosines receptors from receiving them, but it does not stop the production of adenosines, it just stops working for the time being until the effects of caffeine wear off. The reason why sometimes we feel tired and sleepy after drinking coffee is that there’s a buildup of adenosine wanting to bind to its receptors, and this can lead to tiredness.

2. Another reason is that coffee is a diuretic where it can make you urinate often, and leads to a theory that drinking a lot of coffee increases the risk of dehydration, and may lead you to feel more tired.

“First of all, your body loses water when you go to the bathroom. The water loss can reduce the fluid in your blood, which can affect how your cardiovascular system responds to maintain blood pressure and blood flow. Dehydration can lead to a rapid heart rate and low blood pressure. This can lead to feelings of fatigue and sluggishness.

When dehydrated, cells in the body lose fluid volume. When this affects their normal function, it can also lead to feelings of sluggishness. It’s natural to reach for another cup of coffee to counteract this sluggishness, but this can start the cycle all over again.” — Mayo Clinic

3. Lastly adding sugar to your coffee might be the cause of your tiredness. If you drink your coffee with sugar, you may have regular sugar “crashes” after drinking it.

Between caffeine and sugar, our body processes sugar much faster than caffeine. After the sugar is used by our body, we may feel an energy drop. How quickly this happens depends on the person. It could happen within 90 minutes after ingesting sugar.

Is it really the coffee?

The bottom line is coffee won’t directly make us sleepy or tired, but too much caffeine can lead to fatigue. If you can’t give up your coffee habit, you better stick to the daily caffeine recommendation. 400 mg of caffeine per day or less is the suggested caffeine intake without adding sugar, and this will let you enjoy drinking coffee and prevents you from its drawback.

Source Healthline