Why Do I Feel Sleepy After Drinking Coffee?

Tired sleepy woman yawning, working at office desk and holding a cup of coffee, overwork and sleep deprivation concept
  • Caffeine interferes with adenosine, a chemical that builds up in the body and makes you feel sleepy.
  • Adenosine levels may eventually exceed the volume of caffeine in your body, leading to exhaustion.
  • The best way to combat sleepiness is to combine caffeine with a nap.

The relationship between coffee and energy

A recent report by the market research company showed that about 58 percent of Americans rely on coffee for morning energy. And according to the National Coffee Association’s 2020 National Coffee Data Trends Report, the average coffee drinker drinks three cups per day.

However, some people claim that drinking coffee makes them sleepy. Here’s what you should know about coffee’s energizing effects and how it might make you feel tired.

Caffeine may interfere with your sleep-wake cycle

The caffeine in coffee interferes with the natural chemical adenosine, which builds up through the day and makes you sleepy at night. Adenosine levels drop when you sleep, and the cycle starts all over the next day.

Dr. Ryan Greene, an osteopathic doctor specializing in human performance, sports medicine, and nutrition in Santa Monica, California, explains that the levels of adenosine will eventually supersede caffeine’s effects, making us feel tired and sleepy later.

According to a study published in Risk Management and Healthcare Policy in 2018, feeling tired in the morning leads to a high intake of caffeine, which may result in unhealthy sleep patterns.

1. You may have caffeine tolerance.

If your morning coffee doesn’t wake you up the way it used to, you may have built up a caffeine tolerance. However, it doesn’t mean that your sleepiness is caused by your coffee, but that you need more caffeine to feel the same energy.

2. Coffee may provide relaxation.

A single cup of coffee is unlikely to make you feel sleepy. But drinking something warm may provide relaxation and comfort.

Dr. Greene says people can associate coffee with relaxation, like how drinking decaf coffee after dinner helps people unwind.

3. Your coffee may be too sugary.

According to a meta-analysis of 31 studies published in Neuroscience & Biobehavioral Reviews in 2019eating sugary snacks can cause a crash immediately after the sugar rush.

Dr. Greene explains that consuming too much sugar can lead to hypoglycemia, or ‘crash’, and cause a craving for caffeine or sugar for a quick burst of energy, which can lead to a vicious cycle.

4. You may be dehydrated.

Dehydration can cause fatigue. Coffee is a diuretic, meaning it makes you pee. Drinking too much coffee can make you pee often and leave you dehydrated.

But Dr. Greene says it’s unlikely for people to be dehydrated from drinking coffee because coffee still contains water.

5. Dairy may play a role.

Warm milk has long been regarded as a drink that helps you sleep. According to Dr. Greene, it may be attributed to the amino acid tryptophan found in milk, which can cause drowsiness and sleepiness. But he says there is such a small percentage of tryptophan in milk that it would be unlikely to cause a significant effect.

How to drink coffee without getting sleepy

According to a 2018 study published in Nutrients, sensitivity to caffeine may be genetic. Still, there are things you can do to maximize coffee’s energizing capabilities while minimizing its side effects.

  • Reduce your caffeine consumption to break out of the “coffee cycle.” Stick to one to two cups of black coffee daily, recommends Dr. Greene.
  • Avoid adding sugar or syrups to your coffee to avoid a sugar crash.
  • Try plant-based milk to determine if your fatigue is caused by dairy.
  • Consider switching to decaffeinated java or tea.

A “coffee nap” may make you less tired

According to a study of 12 cab drivers published in the journal Psychophysiology, drinking 200mg of caffeine before a 15-minute rest period improved alertness and reduced incidents during an afternoon drive than when taking a nap or drinking coffee alone.

According to some studies, it seems that a brief amount of sleep can reduce adenosine levels in the body, so caffeine deals with less adenosine when it kicks in.