How does caffeine affect my sleep?

Watch out if you’re among those who work at night and sleep during the day: there’s evidence that coffee can really tie a knot in your attempts to get some sleep when you need it most.

According to a study led by a Canadian researcher in Montreal, caffeine interferes with sleep and this effect worsens with age. For shift workers, who need to sleep during the day, caffeine can really antagonize sleep.

What this study pointed out is the fact caffeine can have unintended consequences. Many people who enjoy coffee claim that they can sleep like a baby after drinking coffee, and that it doesn’t affect them as significantly as others. That’s not necessarily true. If you put these self-proclaimed caffeine warriors into sleep labs, you’ll find their sleep fragmented. They don’t get high-quality sleep even though they think they do.

This is lesson for all, not just shift workers who are in a unique situation. Don’t fool yourself into believing you’re superhuman and that caffeine doesn’t work on you. Nice try. While it’s true that everyone’s tolerance and metabolism for caffeine may be slightly different, that doesn’t mean some of us get a free pass on its negative consequences to sound sleep.

There are two major effects depending upon the dose of caffeine and how tolerant you are to its effects upon your body. First, a typical cup of coffee will double the time it takes you to fall asleep. This is called your sleep latency. Second, coffee will reduce the amount of deep sleep you get and induce more nighttime awakenings. This is unfortunate because you need those deeper stages of sleep for healing and memory consolidation. In contrast, caffeine has no significant effects upon the amount of REM or dream sleep you get each night.

Caffeine should be avoided in the evening if you have sleep problems. Drinking too much caffeine tends to reduce your total sleep time and makes it more likely that you'll wake up during the night. In general, it's best to limit caffeinated beverages to 2 cups per day. (Remember - most mugs contain 2 cups of liquid.) When calculating your caffeine intake, remember to include caffeinated sodas in addition to coffee and tea. Most hot chocolate has very little caffeine.

Caffeine is a stimulant, so drinking caffeine can interefere with a good night's rest. Because caffeine has a long half life, it's effects can persist for many hours after you drink it. So anyone with difficulty falling or staying asleep at night should not consume caffeine after noon.

Avoid drinking caffeinated beverages after noon, because the caffeine may interfere with your sleep. Even modest amounts of caffeine can interfere with sleep. It's important to note that even when caffeine doesn't interfere with the ability to fall asleep, it can reduce the amount of time spent in deep sleep, thus compromising the quality of sleep.