Sleepy course 😴 Day 22

Well, yesterday I promised to tell you about caffeine. 🙂 I’m sure, you’ll find it interesting. I noticed that many people like tea and some can’t function without a morning cup of coffee.

Caffeine and health ❤️

I think the benefit of getting rid of the habits we discussed yesterday is rather obvious. Caffeine’s case is harder, there are pros and cons.

For one, people who drink coffee live longer on average as evidenced by a large systematic review, that included 21 studies with a total sample size of 997,000 people. The studies were conducted across many years and during this time almost 122,000 were registered,

Below is a chart, that shows any-cause mortality risk on the Y-axis and the number of coffee cups per day on the X-axis

And here’s a similar chart but with the risk of dying from a cardiovascular disease plotted on the Y-axis instead.

Putting the risk of dying from cancer on the Y-axis reveals a different picture. But as you can see, a couple of cups a day are still associated with lower risk.

Let’s unravel these charts. People who drink on average 4 cups of coffee are on average 16% less likely to die from any cause. Higher consumption leads to an increase in all-cause mortality risk but it’s still lower than for those who abstain from coffee.

Coffee consumption is also associated with a lower risk of diabetes and obesity.

Right now you might think that coffee is this heavenly healing drink, that’s legal and easily available. I have to make a caveat, however. 🙂 Those studies though powerful are still observational. Based on them, we can’t conclude that anyone who wants to live longer should drink more coffee. The studies don’t show a causal link, they only demonstrate a correlation. The correlation allows us to only expect a positive effect of coffee on health and not know there is one for sure. However, you can still take it into account when making a decision.

Caffeine and productivity 🚀

There are no surprises. Research confirms that caffeine, indeed, improves concentration, makes people more energetic, and is effective against drowsiness. This is true.

Caffeine and sleep 😴

Finally, we’ve got to the sleep part. Unfortunately, I don’t have good news for tea and coffee lovers. Research shows those drinks negatively affect sleep quality. Especially, when taken in large quantities before bedtime.

Moreover, the negative impact is observed across almost all of the important sleep indicators - total sleep time and time-to-fall asleep, the number of waking-up times during the night, the percentage of SWS and REM sleep.

There is even an impact on melatonin levels. One study showed as much as 30% less melatonin secretion during the nightly peak after participants drank 5 cups of coffee a day for 7 days.

Cheer up, there is a light at the end of this “caffeine tunnel”. 🙂

Most studies show that a couple of cups of coffee or tea in the morning have almost no impact on sleep.

It happens because a coffee cup starts working 30 minutes after you drank it. After 1.5 - 2 hours the effect wears off, and after 3-7 hours it completely exits your body.

So, just try to avoid caffeine during the second half of the day. Look into herbal teas, some people find them very tasty. 😉

Task:

1. Replace green/black tea and coffee with herbal teas during the second half of the day.
2. Enjoy your evening ritual. ❤️

The studies:

• Coffee, caffeine, and sleep: A systematic review of epidemiological studies and randomized controlled trials
• Coffee consumption and mortality from all causes, cardiovascular disease, and cancer: a dose-response meta-analysis
• The Role of Sleep Hygiene in Promoting Public Health: A Review of Empirical Evidence