Most of us drink coffee with the expectation that it will give us the energy to power through the day, so it can be puzzling when it has the opposite effect and coffee makes you sleepy instead. The reason this happens can depend on your daily caffeine intake, how you make your coffee, and how your body processes the coffee you drink. First, let’s look at how your body processes caffeine. The stomach and intestines absorb your coffee. Then, it reaches your bloodstream where it’s carried all over the body. In the brain, this caffeine binds with specific receptors called adenosine receptors. Adenosine is responsible for making you tired and sleepy. By binding to the receptors, caffeine stops your brain from reacting to the adenosine and makes you feel alert. Once the effect of the caffeine wears off, all the accumulated adenosine can make you feel tired. How long it takes for the caffeine to wear off is controlled by your genetics and lifestyle. Sugar can affect your coffee Another common reason that coffee can make you sleepy is how much sugar you put into your drink. Sugar or any sweetener like cream, honey, or syrup will cause a spike in your blood sugar levels. The more sweetener you use, the bigger the spike, and subsequently a big sugar crash. This dip in blood glucose levels will leave you tired and lethargic. You can prevent this by limiting the amount of sweetener you add to your coffee and balancing your coffee intake with high protein snacks. Coffee can dehydrate Coffee is also a diuretic, meaning it causes water loss through urine. If you drink a lot of coffee, you may notice that you need to use the restroom more often. This can leave you dehydrated, which also makes you feel tired and sleepy. You can fix this by not drinking more than 4 cups of coffee a day and drinking plenty of water. In some cases, mold can accumulate on your coffee if it’s old and not stored properly, which can also make you feel sleepy. Throw out moldy coffee immediately. So, if coffee makes you sleepy instead of energized, check to make sure your coffee is fresh, reduce the amount of sweetener you use, stay hydrated, and try not to drink more than 4 cups or 400 mg of caffeine a day.