How to use the coffee kick calculator
Thanks to the stimulating properties of caffeine, coffee is the number one drink when we're finishing a project or cramming before an exam. But how much and when exactly should you drink to ensure you'll remain focused until the end of the exam you've been studying for the entire night?
Our calculator predicts the level of alertness and shows it as a cool visual graph, depending on the time you've slept and the dose of caffeine you've ingested. It uses a scientifically proven formula based on research on soldiers in a state of sleep deprivation.
How to use:
- Enter how rested you are. Did you sleep well the whole night? Or maybe it was a very short night for you? Include the time you woke up today.
- Input your caffeinated drinks. You can plan your day with up to five different caffeine drinks. For each one, specify the type, time of consumption, and number of servings.
- View your alertness graph. The calculator will show you a 24-hour prediction of your alertness level based on your sleep and caffeine intake.
What you can see on the graph:
- Alertness — we assumed that your alertness is 100% immediately after a full night of sleep. Alertness is a measure of your reflex and ability to stay focused. The higher it is, the better for you.
- Response time — it's a negative measure of your reflex — the sleepier you are, the slower you react. It tells you how much time you need to respond to any stimulus. You surely want to keep it as low as possible.
- Reaction speed — it's a positive measure of your reflex — the more energetic you are, the higher your speed (mental and physical).
The caffeine effect formula
The formula we used in our calculator was developed by a team of scientists in the U.S. Army Medical Research and Materiel Command, Fort Detrick, Maryland. They described it in detail in the article titled A Unified Model of Performance for Predicting the Effects of Sleep and Caffeine.
It turns out that about 40 percent of U.S. soldiers sleep only five hours a day (and even less in extreme situations such as combats), while the Centers for Disease Control and Prevention says that ordinary people need eight to nine hours of sleep. Scientists thus decided to conduct research to keep the army in excellent form throughout the day.
They assessed the soldiers' alertness using a unified performance test in 7 different sleep deprivation schedules: from 5 hours of sleep per night to continuous sleep loss for 85 hours. They tested six different caffeine doses: from placebo to repeated 200 mg doses to a single dose of 600 mg.
What is caffeine, actually?
Caffeine is the most popular psychoactive drug in the world, mostly recognized for its ability to alleviate fatigue. It's a chemical compound naturally found in coffee beans, tea leaves, and a few less-known plants: kola nuts, guarana berries, and yerba mate leaves.
According to comprehensive research, caffeine can influence objective and perceived cognitive performance by increasing alertness and wakefulness. The impact of caffeine appears to be greater under conditions that would negatively impact performance, such as acute caffeine withdrawal or sleep deprivation.
How much caffeine is in different drinks?
In coffee, the caffeine content depends on the kind of beans, roasting, and brewing process. A similar principle applies to tea: different types of tea leaves, growing conditions, processing practices, and brewing techniques have an impact on the energizing properties of the drink.
| Drink Type | Standard Size | Caffeine per Portion |
|---|---|---|
| Espresso | 1 fl oz (30 ml) | 75 mg |
| Filtered Coffee | 8 fl oz (236.6 ml) | 142 mg |
| Instant Coffee | 8 fl oz (236.6 ml) | 94.5 mg |
| Latte | 8 fl oz (236.6 ml) | 45 mg |
| Flat White | 6.4 fl oz (190 ml) | 90 mg |
| Black Tea | 8 fl oz (236.6 ml) | 35.5 mg |
| Green Tea | 8 fl oz (236.6 ml) | 21.5 mg |
| Yerba Mate | 8 fl oz (236.6 ml) | 71 mg |
| Energy Drink | 12 fl oz (330 ml) | 109 mg |
| Energy Shot | 2 fl oz (60 ml) | 198 mg |
| Coke | 12 fl oz (330 ml) | 33 mg |
| Diet Coke | 12 fl oz (330 ml) | 43 mg |
How much caffeine a day can you have?
Scientists agree that 400 mg of caffeine is considered a maximum safe everyday dose. You'll find this much in three cups of strong filter coffee, five espressos, or ten small cans of Coke.
The same review suggested that women of reproductive age shouldn't consume more than 300 mg of caffeine per day, and children should consume less than 2.5 mg per kilogram body weight.
Signs that you're having too much:
- Headaches — caffeine can trigger both light headaches and migraine attacks
- Trouble falling asleep
- Fast and strong heartbeat
- Nervousness, irritability
- Frequent urination and bowel movements
- Stomach discomfort or heartburn
- Fluttering hands
Remember that everyone metabolizes caffeine at a different speed — some people are more sensitive to it than others.
What to do after sleep deprivation?
You probably feel exhausted, but if that's not the case, don't let yourself believe your body took such effort lightly. Take a well-deserved rest! In your everyday routine, remember to get hydrated, exercise, and eat healthily. Make sure you don't strain yourself like this too often!