192 nights of my sleep were tracked earlier this year and I was surprised with what I learned.
We spend 30% of our lifetime asleep, and last year I became curious to learn more about sleep (and went on to read 5 books on it). As an experiment, I decided to track my sleep, not to change it, but to become more aware of how I sleep and how my habits potentially impact my sleep.
Between January and August 2016, I tracked 192 nights of my sleep using an app called Sleep Cycle. Included in the app is a feature called “sleep notes”, which allows you to take customized notes on daily basis. The app gave me an export of all my sleep data (including sleep notes) in a CSV format, which I took a few hours to organize (and learned a number of new spreadsheet functions) recently.
Note: there are many sleep tracking apps available in the app stores, all of them claim to track “sleep quality”. At the start of my experiment, I used 3 sleep tracking apps and while they all tracked what time I went to bed, how long I spent in bed and what time I woke up accurately (as you’d expect), they all had very different ratings for my sleep quality. That led me to not trust the sleep quality data and discard the sleep quality data completely for this experiment.
Every month at our company, we host Lightning Talks, which are an opportunity for anyone on the team to give a short presentation sharing what they have learned, be it related or not to the business. The data below is from my first Lightning Talk sharing my experiment with tracking my sleep.
1. I sleep more than I think I do
7 hours and 27 minutes is the average time I slept per night over the 192 nights of my sleep being tracked. And that’s longer than I would have thought. You’ll see from the data that on weeknights, my average sleep time is closer to 7 hours (very consistently) but on weekends, it is closer to 8 hours and 30 minutes.
2. I go to bed later than I think I do
10:50 PM is the average time I go to bed each night, and while I often like to believe I go to bed closer to 10 PM, the data showed me otherwise. Friday evenings are a “late night” for me (11:11 PM on average) and Monday through Wednesday nights being “early” (10:30 PM on average). Not too much variability overall though.
3. Waking up early is something I really do value
6:19 AM is the average time I wake up, which is not that big of a surprise. I “sleep in” on Friday and Saturday mornings (7:35 AM and 7:22 AM respectively) and wake up earliest on Mondays (5:32 AM). Waking up early has become a ritual for me, and something I really do enjoy, value and cherish. It gives me an opportunity to meditate, practice yoga, and journal, all of which help center and ground me ahead of an active day.
4. Using screens at night happens more often than I think
61% of the nights tracked I had used a screen at night, and although that’s probably lower than society’s average, it’s way higher than I thought it would be! There is plenty of research about the connection between screen use at night (be it TV, laptops or smartphones) and it’s impact on sleep quality (and the interference with melatonin production in the brain, a chemical that is needed to trigger the start of the “going to sleep” process).
Although I did not measure sleep quality, nights I used a screen I did go to sleep 13 minutes later than average.
I do not have email on my phone, barely browse the web, do not regularly watch TV and do not personally use social media, so screen use at night does not happen that easily. I believe my screen use would have been a combination of working into the evening, going to the movies, texting with friends or randomly watching Netflix.
In case you’re wondering how I tracked this (and the points to follow), I kept “sleep notes” within the Sleep Cycle app, so each night before going to bed and starting the sleep app, I had a checklist of sorts to capture a few predetermined habits I wanted to track. And then when I extracted the data, I was able to see what habits I had practiced during the day and correlate that with my sleep data.
5. Reading at night is great for my sleep
52% of the nights I read before going to sleep. Reading at night was not a regular habit for me before this experiment and an intention I had set, knowing I would be tracking my behaviour likely encouraged me to do this more consistently (and I’m pleased that I read half of the nights, it is more than I thought I did). I slept 9 minutes longer and went to bed 14 minutes earlier on nights I read.
Tuesday, Wednesday and Thursday nights had a lower frequency of me reading, likely because those are often my travel days (I live in Toronto but am normally in New York Tuesday through Thursday). And Saturday I often would be at my parents place or out with friends. In all of these instances, I probably did not have a book with me. And I do not read books on screens, I choose real-life books (usually from the library).
6. I consistently eat more on Sundays
I asked myself each night if I felt I had “more food” or “less food” during the day. This may seem subjective, but any inaccuracy would be consistent as it was always me asking and me answering the same question (over 192 nights). I was not surprised that 60% of the days I ate more, but was surprised to see that it often happened on Sundays (my mom can take credit for that). Days I ate more I ended up sleeping 9 minutes longer and went to be 6 minutes sooner. Thursdays I ate less, likely because I often travel on Thursday nights and probably end up having a light dinner (or no dinner).
7. Eating less during the day means I sleep less
Conversely, days I ate less food, I slept less and went to bed later. I am not sure if that is because I needed less sleep or because I was occupied with other activities those days so much that both food and sleep were reduced as a byproduct. Eating less food does not mean only having an apple (as the simplicity of the image may lead you to believe), I probably still had 3 meals but was more mindful of the quantity of food I consumed.
8. Caffeine is truly optional for me
I do not regularly drink caffeine and when I do, it’s tea. 36% of the days tracked I had tea, which was actually more than I expected. Days I have tea are concentrated on Tuesday, Wednesday and Thursday (also the days I am on the road and often in New York). I did sleep less on average days I had caffeine and went to be slightly earlier, however once again, as I did not track the quality of my sleep, it is difficult to tell the relationship.
About two months ago (before looking at this data and after I had stopped tracking my habits and sleep), I decided to experiment with cutting out tea altogether. It was a spur of the moment decision one morning and I was curious to see what would happen. No surprise, nothing happened. And I am completely fine with no caffeine. I no longer have tea, even on my travel days.
9. I sleep more when stressed
Now we are getting into the most interesting part for me. Similar to the food question, I asked myself each day if I felt “more calm” or “less calm”. Less calm means I felt stressed at some point during the day. Could be a small dose or large dose of stress, doesn’t matter. If I felt any type of stress during the day, I marked it less calm.
I felt stressed only 13% of days, which was fewer than I remember, which says to me that we may remember days we feel stress more than days with a lack of stress. I slept 18 minutes longer and went to be 28 minutes sooner on days I felt stressed. Feeling burned out and tired likely go hand-in-hand with feeling stressed, and showed up in my sleep data.
Mondays are when I have a day full of internal team meetings (so my team can take partial credit for when I feel stressed on those days), Wednesdays I am often in New York and Sundays I am usually with my family.
10. I am generally a calm person
87% of the days tracked I felt calm, i.e. not stressed. I’ll share credit for this with all of you who interact with me on a regular basis and my personal practices, which include meditation, yoga, journaling and reading.
11. I value sleep now a lot more than I used to
I used to have a negative relationship with sleep, seeing it as something optional and feeling that it was a trade-off I was willing to make for other experiences in life. I’ve done a 180 turn on that feeling now and have a positive relationship with sleep. That does not mean I sleep all the time (my average time in bed is 7 hours and 27 minutes), it means that I value, respect and understand the importance of sleep. And as such, now pay attention to all of the other habits and routines in my life that may be impacting my sleep.
This experiment has been valuable as a self-awareness tool, surprising me with new insights that were contrary to my previously held assumptions and beliefs.