Caffeine and sleep – what you need to know

Coffee is part of the daily ritual for millions of people around the world. But does the caffeine in your favourite hot drink (or cold drink, for that matter) interfere with your sleep? We look at the science.

Caffeine occurs naturally in coffee beans, as well as 60 other types of plants, such as certain varieties of tea leaves and cocoa. Caffeine is thought to be the most common drug on the globe. Classified as a stimulant, coffee is responsible for an estimated 54% of all caffeine assumption worldwide.

It takes just 15 to 20 minutes to feel the effects of a cup of coffee, and your caffeine levels will peak at the 30-minute mark and stay there for at least another half hour. From here, the “caffeine residue” will stay in your system for up to six hours, depending how you take your coffee and what your metabolism is like.

Caffeine works to wake us up and keeps us buzzing by disrupting adenosine, a substance that helps promote sleepiness. It blocks those receptors, either reviving you during waking hours, or, if you drink it too late in the day, disrupting your sleep.

A normal daily dose of caffeine is considered to be anywhere from 50 to 200 mg. A single espresso contains about 63mg and a cup of brewed coffee about 95mg. A can of your favourite soft drink can have between 40 and 60mg of caffeine.

While a caffeinated drink can perk you up, it can also impact the quality of your rest by knocking your circadian rhythm sideways. Your circadian rhythm is the control centre for your body’s sleep and wake times. A disrupted body clock can damage your sleep quality and reduce your total sleep time.

Caffeine also decreases deep sleep, a crucial phase for functions like cell repair. Consumption within six hours of bedtime can reduce your sleep time by a full hour. That affect becomes more profound in older adults because the body takes longer to process caffeine.

There’s also evidence that higher levels of caffeine are problematic, especially for those with high blood pressure or cardiovascular issues.

But, if you are looking to cut down on your caffeine intake, it’s not a great idea to go cold turkey. Withdrawal symptoms can include: sleeplessness, irritability, headaches and low energy.

Instead, experts suggest tweaking your consumption to pare it down to the 300 to 400 mg a day range (about four cups max), then drop it down from there. Alternatively, aim for sources of caffeine with lower amounts. For example, tea has more caffeine than coffee gram for gram, but there’s less caffeine per cup.

For more news and for expert sleep advice, visit our Restonic Sleep Blog.