Most people use coffee as fuel to feel alert and energized during the day. Besides perking up tired office employees, it's become a luxury good, a hobby, and an opportunity for people to meet up.

The benefits don't stop there. Coffee has high amounts of nutrients and antioxidants, and studies have linked the beverage to lower risk of developing type 2 diabetes and Alzheimer's disease. The caffeine present in coffee can improve your mood and brain function as well.

But that caffeine also has a dark side. Regular consumption leads to tolerance, where the drinker needs a higher dosage to get the same brain-boosting effects as before, and abstinence can lead to withdrawal symptoms such as headaches and irritation.

Drinking coffee could also be lowering the quality of your sleep. We commonly hear advice about not drinking coffee too late and how it prevents a good night's rest. But exactly how late is too late?

Coffee's Effects On Our Sleeping Patterns

Researchers from the Sleep Disorders & Research Center at Henry Ford Hospital and Wayne State College of Medicine embarked on a study to analyze how caffeine disrupts sleep when consumed at different points in time during the day.

The volunteers included 12 healthy men and women who were normal sleepers and regularly consumed moderate amounts of caffeine. During the study, they maintained their normal sleep routines with bedtimes from 9 pm to 1 am, and wake times of 6 am to 9 pm. They slept somewhere between 6.5 to 9 hours each night without napping during the daytime.

Participants were given a fixed dose of caffeine, along with placebos, at 0, 3, and 6 hours before bedtime. 400 mg of caffeine was administered, which is equivalent to around four cups of coffee.

Researchers monitored signs of sleep disturbance using a sleeping monitor and here's what they found:

At 0, 3, and 6 hours before bedtime, caffeine had a significant effect on sleep disturbance. Even caffeine consumed 6 hours before bed affected sleep amounts by over an hour.

Sleep quality was diminished when caffeine was consumed at all three points during the day. Compared to the placebo, there was a significant amount of time spent awake during the night, including when caffeine was consumed 6 hours before.

But here's the most surprising result:

The perception of caffeine's effect on the body was not a direct measure of how it affected sleep. In other words, participants might not have felt the caffeine in their body, but it still affected their sleep quality for the worse.

When caffeine was consumed at 0 and 3 hours before bedtime, participants perceived that it was a disruption to their sleep. When caffeine was consumed 6 hours before bed, they did not report any effect to their sleep quality. But the sleep monitor showed a different story.

The interesting lesson from this study is that we shouldn't fully rely on our own perceptions to judge how caffeine is really affecting us, especially when it comes to sleep. That afternoon coffee you're taking to stay awake could be keeping you up for longer than you might think.

Optimizing Caffeine in Our Day

Even though coffee can be affecting your sleep, it doesn't mean that it's time to cut it out completely. There are a number of benefits linked to coffee, and keeping your brain alert is one of the main reasons why many of us drink it in the first place.

Instead, what's important is managing what we drink throughout the day. Here are a few ideas for managing your coffee consumption:

  • Set a cut off time for coffee at 2 pm. Caffeine takes a while wear off and can cause sleeping problems, even if you don't feel it. For this reason, it's best to limit coffee consumption for the morning hours and limit it to early afternoon at the latest.
  • Limit coffee to a maximum of four cups per day. According to the Mayo Clinic, adults shouldn't be consuming more than 400 mg of caffeine per day, which equals about four cups of coffee. Too much caffeine can cause increased anxiety and irritability. If you have the urge to drink more coffee, choose decaffeinated.
  • Reduce caffeine intake as the day progresses. You're most likely going to need caffeine early in the morning, when you're probably feeling a bit groggy and need a boost. This is the best time to drink coffee if you need it. Later in the day, wean off the caffeine by opting for tea (tea with milk is a good substitute) or decaffeinated coffee so you can be caffeine-free by evening.
  • Use a smaller mug. When we fill use a cup, we're tempted to fill it up to the top to give ourselves more. When given a choice between a larger and a smaller mug, choose the smaller one to give yourself the illusion that you're drinking more. Your environment counts.

Enjoy Your Hot Beverage, But Responsibly

I love drinking coffee. That first sip, the soothing aroma, and the rising steam combine to make it a comforting drink.

But I also love a good night's sleep. For coffee, that means drinking at the right time and being mindful of how much is too much. We have a responsibility to ourselves to stay healthy, productive, and get enough rest at night.