Tiredness is a physiological and psychological state of exhaustion and depleted energy (often accompanied by a desire for sleep) caused by adenosine build-up, which coffee can paradoxically worsen. While drinking coffee may initially boost alertness and keep you awake, excessive caffeine intake (such as 7 cups of coffee per day, which can amount to 600-700 milligrams of caffeine) can lead to tiredness, fatigue, and daytime sleepiness due to adenosine build-up once the caffeine wears off, according to a 2005 study published in the Sleep Medicine Journal.
So, why does coffee make me sleepy? The answer lies in the complex interplay between caffeine, adenosine, and your body's natural sleep-wake cycle, rather than the coffee itself directly inducing sleepiness. Caffeine temporarily blocks adenosine receptors in the brain, preventing the feeling of tiredness. However, when caffeine levels decline, the accumulated adenosine floods the receptors, leading to a crash and heightened fatigue.
Interestingly, a 2013 study from the Department of Clinical Neuroscience at Karolinska Institutet in Sweden linked genetic variations in adenosine receptors to ADHD, suggesting some individuals may be more susceptible to caffeine's rebound effect and experience heightened tiredness after its initial boost.
Caffeine in coffee is not the only stimulant that can provide a temporary energy boost. For those who look for an alternative to coffee to stay awake and avoid potential crashes, there are various other options available. Regular physical activity can increase energy levels, staying hydrated can prevent dehydration-related fatigue, getting sunlight can help regulate sleep-wake cycles, and following a healthy diet can provide sustained energy throughout the day.
Why Does Coffee Sometimes Make Me Tired?
The primary reason coffee can make you tired and sleepy is due to the adenosine rebound effect, as noted in a 1995 study in Progress in Neurobiology Journal. Caffeine, a central nervous system stimulant found in coffee, acts as an adenosine receptor antagonist, particularly at A1 and A2A receptors in the brain. This prevents adenosine, a neurotransmitter that promotes sleep and relaxation, from binding and signaling tiredness. Caffeine blocks these receptors, temporarily preventing adenosine from signaling tiredness. However, the body continues producing adenosine during this time.
When the caffeine wears off, the accumulated adenosine floods the receptors, leading to a sudden and significant increase in sleep pressure and resulting in a feeling of fatigue. This 'coffee-makes-me-sleepy' phenomenon has been documented in a 2004 clinical trial by Hans-Peter Landolt from the Institute of Pharmacology & Toxicology at the University of Zürich.
A diagram illustrates how does caffeine in coffee affects the sleepiness by blocking adenosine receptors in the brain.
Additional reasons why coffee might make you tired include chronic caffeine consumption and developing tolerance, caffeine's effect on sleep quality at night, genetic variations in adenosine receptors, blood sugar fluctuations, as well as other ingredients in your coffee.
- Chronic Caffeine Consumption and Tolerance: Chronic caffeine consumption and tolerance is one reason why you may feel sleepy after coffee. A 2021 study by Janine Weibel at the University of Basel's Centre for Chronobiology found that regular caffeine intake (approximately 3 × 150 mg daily) can cause the body to adapt, reducing its response to caffeine's stimulating effects. While not significantly altering total sleep time or subjective sleep quality (how well a person feels they slept), caffeine consumption reduced EEG (electroencephalogram, a test that measures brain waves) power density in the sigma frequency range 12–16 Hz during non-rapid eye movement (NREM) sleep (the stage of sleep without rapid eye movements) by about 20%. This indicates a disruption in slow-wave sleep (SWS) (the deepest stage of NREM sleep), which is essential for feeling rested and refreshed. Despite falling asleep faster and sleeping more efficiently, this lack of deep sleep can lead to overall tiredness.
- Caffeine's Effect on Sleep Quality: Caffeine's effect on sleep quality is one of the reasons why some get sleepy after drinking coffee, even though it initially provides an energy boost. Caffeine can help you stay awake, but it can also negatively impact your sleep quality. Research has shown that consuming caffeine, particularly in the evening, can make it harder to fall asleep and reduce overall sleep quality. A 2006 randomized controlled trial in the Journal of Sleep Research found that a 200mg dose of caffeine lengthened sleep latency by 10-15 minutes, reduced sleep efficiency by 5-10%, and decreased deep sleep stages by 20-25%, while increasing lighter sleep stages by 10-15%. This can lead to less restorative sleep, leaving you feeling more tired the next day.
- Genetic Variations in Adenosine Receptors: Genetic variations in adenosine receptors may be one reason why coffee can make you sleepy. A 2007 study in Clinical Pharmacology & Therapeutics found that a specific variation in the adenosine A2A receptor gene (ADORA2A) affects how sensitive people are to caffeine's impact on sleep. Individuals with this variation who are sensitive to caffeine tend to experience poorer sleep quality after consuming it, potentially leading to increased tiredness.
Other possible reasons coffee makes you tired include blood sugar fluctuations, as caffeine may cause a temporary spike followed by a crash leading to fatigue. Additionally, dehydration from coffee's diuretic effect, individual variations in caffeine sensitivity, and different types of coffee drinks can contribute to tiredness.
Does adding milk to coffee make you more tired? Evidence suggests that milk may influence how coffee affects sleepiness due to its tryptophan content. Tryptophan, an amino acid that helps produce sleep-regulating hormones serotonin and melatonin, is found in high levels in milk. A 2023 review in the Nutrición Hospitalaria Journal from researchers at the Universidad Complutense de Madrid highlighted that this, along with milk's favorable amino acid ratio, can promote sleep. This may explain why warm milk alone makes people sleepy. However, the overall impact of milk in coffee would depend on the balance between caffeine's stimulating effects and tryptophan's calming effects.
These varying responses to caffeine raise questions about how specific populations, such as individuals with ADHD, might be affected.
Does Coffee Make You Tired if You Have ADHD?
Coffee's impact on those with ADHD (Attention Deficit Hyperactivity Disorder, a neurodevelopmental disorder characterized by inattention, hyperactivity, and impulsivity) is complex and can vary. While caffeine may initially improve alertness, studies suggest a potential link between ADHD and variations in adenosine receptors, which can influence caffeine sensitivity. A 2013 study in Genes, Brain and Behavior found that certain genetic variations in adenosine A2A receptors might increase susceptibility to caffeine's "rebound effect," leading to heightened tiredness as caffeine wears off.
Additionally, a 2020 study in Neuropharmacology showed caffeine's potential to rescue neuronal development (the growth and maturation of nerve cells) in frontal cortical neurons (nerve cells in the brain's frontal cortex responsible for higher cognitive functions) of an ADHD rat model, suggesting a complex interaction between caffeine, adenosine receptors, and ADHD that requires further investigation.
It's important to note that individuals taking prescription medications for ADHD, such as Adderall, Vyvanse, Ritalin, or Concerta, may experience sleepiness, tiredness, and fatigue as a side effect, as indicated by a 2009 study from the Department of Psychology at the University of the Witwatersrand. The study found that those with ADHD who were medicated with methylphenidate (a central nervous system stimulant used to treat ADHD) reported increased sleepiness from morning to afternoon.
Drinking too much coffee while taking ADHD medications can increase blood pressure and heart rate, and combining them may enhance these effects. Therefore, while some individuals with ADHD might experience a temporary energy boost from coffee, others might feel tired, dizzy, or sleepy due to a combination of factors including genetic predispositions, medications, and caffeine's impact on adenosine regulation and sleep patterns.
This table displays types of drinks (including coffee) to use and to avoid for those with ADHD.
What Can You Do When Feeling Tired after Drinking Too Much Coffee?
When feeling tired after too much coffee, whether in the morning or at work, it's important to address the underlying causes and adopt strategies to counteract the effects.
- Start by rehydrating with 500 ml (16.9 oz) of water or mineral water, which will replenish lost fluids and improve cognitive function.
- To combat the dip in blood sugar that often accompanies a caffeine crash, consume a balanced snack containing protein, fiber, and complex carbohydrates for sustained energy release.
- Engaging in light physical activity, such as a 20-minute walk or stretching, can increase blood flow and oxygen levels, promoting alertness and reducing fatigue.
Similarly, if you're feeling tired after drinking too much coffee at work and need to stay productive, strategically incorporate short breaks throughout the day to rest your mind and eyes, allowing for greater focus and productivity upon return. Additionally, consider evaluating your caffeine intake and adjusting your consumption habits to stay awake and minimize the likelihood of experiencing crashes in the future.
How To Stay Awake Without Coffee
These are the nine ways to stay awake without coffee.
- Splash Cold Water on Your Face: The shock of cold water can quickly awaken your senses and increase alertness.
- Listen to Upbeat Music: Put on some energetic tunes that will get your blood pumping and your mind engaged.
- Do Some Quick Stretches or Exercise: Even a few minutes of physical activity can increase blood flow and oxygen levels, helping you feel more awake.
- Spend Time in Natural Light: Exposure to sunlight helps regulate your body's natural sleep-wake cycle, making you feel more alert.
- Switch Tasks or Take a Break: If you're feeling drowsy while working on something, changing tasks or taking a short break can help refresh your mind.
- Socialize or Engage in Conversation: Talking with someone can stimulate your brain and help you stay awake.
- Practice Deep Breathing Exercises: Deep breathing can increase oxygen intake and improve circulation, reducing feelings of fatigue.
- Chew Gum or Suck on a Mint: The act of chewing or sucking can increase blood flow to the head and neck, which can help you feel more awake.
- Try Aromatherapy: Certain scents like peppermint or citrus can have invigorating effects and help combat drowsiness.
Additionally, switching to decaffeinated drinks can potentially help overcome the afternoon slump and reduce the likelihood of experiencing a caffeine crash later in the day.
What Can I Drink to Keep Me Awake besides Coffee?
These are the beverages to drink for those looking for an alternative to coffee to stay awake.
- Green Tea
- Yerba Mate
- Kombucha
- Chai Tea
- Matcha
- Golden Milk
- Water
- Black Tea
- Oolong Tea
- Herbal Tea (with ginseng or peppermint)
- Lemon Water
- Coconut Water
- Apple Cider Vinegar Drink
- Beet Juice
- Smoothies with Spinach and Kale
- Ginger Tea
- Protein Shakes with added green tea or matcha
- Decaf Coffee
Does Decaf Coffee Make You Sleepy?
While decaf coffee contains minimal caffeine (FDA requires that 97% of the original caffeine content must be removed), it can still make some people sleepy due to individual sensitivities to other compounds in coffee or a placebo effect. However, for most people, decaf coffee does not directly cause sleepiness.
For those tired of sacrificing taste for decaf, Powerbean Coffee offers a wide range of premium decaf coffee, from smooth and mellow to bold and robust. We source only the finest beans and use a gentle swiss water process to remove caffeine, preserving the unique flavor profile of each variety.
