If you’re like most people, you probably reach for a cup of coffee more than you would like to admit. It’s safe to say you’re not alone. More than 90% of adults in the United States regularly consume an average of 200mg of caffeine per day. Some studies estimate the average adult daily caffeine consumption is actually more like 300mg. The thing about caffeine is that it can be a relatively safe, non-harmful habit. However, it can also cross the line from a pleasant cup of coffee to a necessity that can impact your sleep and well-being.  

How does caffeine affect your body? 

Caffeine is a stimulant found in foods and beverages like coffee beans, cacao pods, and tea leaves. It’s also created synthetically for energy drinks and medications. 

When you consume caffeine, it’s absorbed quickly into the body through the intestines and then dissolves in the blood. Experts estimate that you feel the maximum effects about 30-60 minutes after consuming. As a stimulant, caffeine increases activity in the brain and nervous system. 

Caffeine crosses the blood-brain barrier and enters the brain. Inside the brain, it blocks adenosine from binding, which keeps you alert and awake. Adenosine is a sleep-promoting chemical. Caffeine also increases physical energy and boosts the circulation of chemicals like cortisone and adrenaline. 

Caffeine and sleep 

Naturally, when talking about a substance that makes you feel alert, the question is, does caffeine really impact your sleep, and how long does caffeine last? Before we dive any deeper, you need to understand that caffeine has a half-life of about five hours. That means that after five hours, half of the caffeine is still in your system. So, it can take roughly ten hours for caffeine to leave your system. 

When it comes to how caffeine makes you feel, multiple factors influence how you metabolize caffeine, including: 

• Genetics 
• Age 
• Time of consumption
• How often you consume caffeine 

Caffeine affects different people in different ways. You may find that caffeine affects you more or less than someone else, and there’s usually a combination of reasons as to why. Some have greater sensitivity, while others need higher amounts to achieve the same effect. 

The most obvious impact of a cup of coffee before bed is that it can make it harder to get to sleep. Because caffeine blocks adenosine, it can reduce sleepiness and may even make your sleep lighter. Older adults may also be more susceptible to caffeine sleep disruption. 

If you find yourself suffering from insomnia, caffeine may worsen the condition. At the same time, caffeine overuse can lead to insomnia symptoms and delay your body clock timing. 

How much caffeine should you have? 

If you find that caffeine doesn’t affect you, it could be down to high tolerance, genetics, or even sleep deprivation. Anyone who guzzled back one too many coffees in a day may be familiar with caffeine soaring through their veins. Symptoms of too much caffeine include: 

• Anxiety 
• Insomnia 
• Digestive problems 
• Headaches
• Nervousness 
• Irritability 

So, how much caffeine should you have? Experts recommend that healthy adults shouldn’t consume more than 400mg of caffeine per day. That’s about four eight-ounce cups of brewed coffee, which could be a lot or a little for you. 

The problem with putting a number on how much caffeine you could consume is that it doesn’t always consider the vast differences in how people metabolize and tolerate caffeine. It’s about finding a level that’s healthy for you. Another factor that makes tracking caffeine consumption hard is the difference in the caffeine in food and beverages. It’s tricky to track how much you’re consuming. Your cup of coffee could contain more than your recommended amount of caffeine for the day, and you have no idea. 

To help you navigate the world of caffeine, here’s a helpful caffeine chart that lists popular brands and caffeine content. It’s surprising to see that just one venti from Starbucks hits your daily intake, and yet a green tea contains only 55mg of caffeine. 

How to deal with caffeine withdrawal 

If you feel overly anxious and experience headaches or insomnia, this could signify too much caffeine. Caffeine addiction symptoms such as frequent night awakening and nighttime anxiety can indicate that caffeine is interrupting your sleep. Also, if you find that you’re very sleepy during the day, despite consuming caffeine, this could be a sign of overuse. 

You may go through caffeine withdrawal and experience headaches, drowsiness, and nausea by cutting out caffeine. Roughly 12 to 24 hours after stopping caffeine, withdrawal symptoms can kick in and last for up to nine days. If you cut back slowly, it can help you to avoid some caffeine withdrawal symptoms. For instance, if you have four cups of coffee a day, bring it down to three, then two, but over several weeks. Eventually, you can introduce decaf options or green tea, which contains less caffeine. Instead of going cold turkey, give yourself the time to reduce your caffeine intake. 

It’s important to remember that it’s not just caffeine that impacts your sleep. Your stress levels, sleep environment, bedtime routine, diet, and exercise all play a role in your sleep hygiene. If you find that caffeine no longer has the same effects, or you're chugging back a lot of coffee, it could be time to cut back. Like most people, caffeine is probably a part of your daily routine. While that’s not necessarily a bad thing, it can cause problems if you’re not careful. When you consume caffeine is just as important as how much because it stays in your system for hours. Be mindful of your caffeine consumption, set a cut-off time, and try to limit your daily intake.