Seems like every month or so, someone sends me a link to some health study involving coffee. I used to read them, but I don’t anymore. People have been drinking coffee for a very long time. A simple observation will tell you we coffee drinkers are not dropping dead like smokers or outliving the non-coffee drinkers. My opinion is the change in a person’s health outcome as a result of coffee is minor and highly personalized. And that effect can change over time.
We all know someone that can drink massive amounts of coffee all day long and sleep like a baby. We might also know someone so sensitive to coffee that a single cup could keep them awake all night long. I know a guy who stayed awake for almost 3 days after drinking several cups of green tea. What affects your sleep will directly affect your health outcome. When studies make blanket statements that coffee prevents this or that, they are failing to look at the individual response to caffeine.
Good Sleep for Good Health
Good sleep is very important for good health. As coffee drinkers, our goal is to consume coffee only up to the point where sleep quality is impaired. About 10 years ago I was drinking an insane amount of coffee every day. From the time I woke up until night, I’d slam mugs of french press coffee. My adrenals were so exhausted by the end of the day, I would fall asleep immediately. But over time I noticed that I was waking earlier and earlier. Despite still being tired, I’d be up making more coffee.
I came up with an experiment. I pushed my last coffee back to 6 PM. My sleep improved. Then I moved my last coffee to 4 PM and it improved again. Then I moved it to 2 PM and saw no additional improvement. So for a few years, I had my last cup of coffee between 2 PM and 4 PM. It yielded me the best quality of sleep.
Collect Data
In the past few years, a movement called The Quantified Self has emerged. With spreadsheets and gadgets, it is now possible to track data about our lives and then adjust behavior. Collect more data and then adjust again. From the Wired article Know Thyself: Tracking Every Facet of Life, from Sleep to Mood to Pain, 24/7/365 by Gary Wolf:
Numbers are making their way into the smallest crevices of our lives. We have pedometers in the soles of our shoes and phones that can post our location as we move around town. We can tweet what we eat into a database and subscribe to Web services that track our finances. There are sites and programs for monitoring mood, pain, blood sugar, blood pressure, heart rate, cognitive alacrity, menstruation, and prayers. Even sleep-a challenge to self-track, obviously, since you’re unconscious-is yielding to the skill of the widget maker. With an accelerometer and some decent algorithms, you will soon be able to record your sleep patterns with technology that costs less than $100.
That article was written in 2009. Today there are now 99 cent apps you can put on your iPod or iPhone that can measure your sleep quality by how much the bed moves. The Sleep Cycle application even makes a nice graph.
Sleep Cycle
Or you could use a wrist-based tracker such as the FitBit.
Fitbit Charge 2 Heart Rate + Fitness Wristband (Amazon USA, Amazon UK, Amazon Canada)
What To Track?
If we can combine data about our sleep with data about our coffee intake then we dial in the optimal level of coffee for us on an individual basis. So far I haven’t used any of the iPhone applications. My goal for this article was to see what I could learn without going high tech. So I just used a simple spreadsheet. Some of the variables that I have tracked or am currently tracking include:
- Date
- Quantity of coffee
- Sleep quality (1 to 5)
- Time of last coffee
- Daytime mood (1 to 5)
- Did I consume chocolate?
What I discovered is that the more complicated you make the tracking, the less likely you’ll maintain the data.
Studying My Data
One of my goals in 2011 was to reduce my coffee intake. Instead of going cold turkey, I did a gradual decline. Tracking my coffee intake allowed me to see my progress. The chart below shows my daily pattern of coffee intake. I also added a 3-day moving average to smooth out the lines for those days that weren’t typical.
My coffee intake from March 24, 2011 – December 24, 2011. The red line is a 3-day moving average.
After my coffee detox, I wanted to learn more about the relationship between coffee intake and sleep quality. Every morning when I woke up, I would assign a score of 1 to 5 for sleep quality. A score of 5 would be perfect sleep. Later I would start tracking the time of the day when I had my last coffee. After almost 3 months of data collection, here are the average sleep quality scores I got.
| Coffee Intake | Sleep Quality |
|---|---|
| 2 | 3.23 |
| 3 | 3.72 |
| 4+ | 3.48 |
Then I divided the data into two groups based on my last coffee intake.
| Coffee Intake | Sleep Q (Last Coffee BEFORE 1 PM) | Sleep Q (Last Coffee AFTER 1 PM) |
|---|---|---|
| 2 | 3.42 | 3.00 |
| 3 | 3.50 | 3.76 |
| 4+ | 3.25 | 3.52 |
So far it appears to me that my sweet spot is 3 coffees a day, where the last coffee is consumed after 1 PM. Going forward, I plan on figuring out the optimal hour to consume my last coffee.
Dialing in Your Sweet Spot
I believe that doing a few months weeks of tracking your coffee intake and sleep quality will tell you more about the benefits of coffee than any health study. Look at the data and dial in the level that works best for you. Does your sleep suffer? How much? Only you can answer these questions.
Quantified Self Caveat (October 2014)
The first version of this article was written in January 2012. Since then I’ve learned a lot about self-tracking. Keep your experiment short. If you don’t see obvious patterns, then one probably doesn’t exist. Human data can be messy. Many other items can affect sleep quality. Coffee is just one item.
Michael Allen Smith
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