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Coffee is known worldwide for its ability to boost energy, sharpen focus, and keep sleepiness at bay. In fact, between 2023 and 2024, coffee consumption in India surpassed one million bags, each weighing 60 kilograms. However, for some people, instead of providing a jolt of energy, coffee leads to feelings of drowsiness and tiredness. If you’ve ever wondered why coffee makes you feel sleepier instead of more alert, the answer may lie in the complex interplay of hormones, genetics, and lifestyle habits.
To understand this phenomenon better, the OnlyMyHealth team spoke with Dr. Varsha Kachroo, Consultant Endocrinologist, Yatharth Super Speciality Hospital, Noida Extension. She shared several key reasons why some people experience sleepiness after consuming coffee.
The Dopamine Crash
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Dr. Kachroo explains, “Caffeine causes a rapid increase in hormones such as dopamine, which causes an increase in energy and concentration. But as the levels of these hormones decline, some people may experience what is called a ‘crash,’ leading to feelings of sleepiness and tiredness.”
Dopamine is often referred to as the “feel-good” hormone. When caffeine boosts dopamine production, you feel energised and alert. However, once the caffeine wears off and dopamine levels drop, your body can experience a sharp dip in energy, leaving you feeling lethargic and tired.
Sugar Content In Coffee
Dr. Kachroo also points out the role of sugar, “Many caffeinated drinks contain a lot of added sugars, which leads to a rapid increase in blood sugar levels, triggering the release of dopamine. As the body starts the disposal of sugars, this happy feeling can go off, again leading to feelings of lethargy and sleepiness.”
Sugary coffee drinks, like flavoured lattes or frappés, might give you an initial burst of energy due to the sugar content. However, as your body processes and lowers your blood sugar levels, you may feel a slump in energy, contributing to sleepiness.
Calorie-Dense Ingredients
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Some coffee beverages are more than just coffee and caffeine. Dr. Kachroo notes, “Some coffee drinks may contain other ingredients like milk, chocolate, ice cream, or sugary syrup, making them calorie-dense. This can cause a rapid increase in calorie intake, leading to feelings of fullness and sleepiness.” Drinks loaded with calories can signal your body to slow down for digestion, leading to a post-meal lethargy, also known as the “food coma.”
When Caffeine Plays A Paradoxical Effect
Interestingly, for some individuals, caffeine can have the opposite effect. Dr. Kachroo explains, “In some cases, caffeine can have a paradoxical effect, where it actually increases the desire to sleep. This is more common in people who are sleep-deprived or have disrupted sleep patterns.”
If you’re already exhausted, caffeine may not work as expected. Instead of keeping you awake, it can magnify your body’s need for rest, making you feel sleepier.
Genetic Differences
Our body’s response to caffeine can also be influenced by genetics. Dr. Kachroo says, “Research suggests that the differences in genetic makeup can affect how people respond to caffeine. Some people may be more prone to sleepiness after consuming caffeine due to their genetic interplay.” Some people metabolise caffeine quickly, while others do so slowly. This can determine whether caffeine keeps you alert or has little effect at all.
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Medication
Another factor to consider is how caffeine interacts with certain medications. Dr. Kachroo highlights, “Caffeine can interact with certain medications, such as sedatives or antidepressants, increasing their effects and leading to increased sleepiness.” If you are on medication, the combination with caffeine might amplify drowsiness rather than prevent it.
Caffeine Tolerance
Regular coffee drinkers can build up a tolerance to caffeine. Over time, the body becomes accustomed to the effects of caffeine, requiring higher doses to achieve the same level of alertness. But increasing caffeine intake to compensate can backfire by negatively affecting sleep quality. This can create a cycle of fatigue, where you feel more tired despite drinking more coffee.
Your Sleep Quality Matters
A 2020 study revealed another interesting connection between coffee and sleep. The study found that drinking coffee in the morning after a poor night’s sleep led to higher glucose intolerance and elevated blood glucose levels. However, skipping the coffee after a poor night’s sleep did not have this effect. This suggests that poor sleep, combined with caffeine, may worsen your body’s ability to manage energy levels.
Bottomline
While coffee is often celebrated for its energising effects, it doesn’t work the same way for everyone. Factors like hormone crashes, sugar content, calorie-dense ingredients, genetics, medications, and sleep patterns can all influence how your body reacts to caffeine. If you find yourself feeling sleepy after coffee, it might be worth examining these factors and adjusting your caffeine intake accordingly.