Sleep debt insights on Evidation

Evidation Members tell us they love seeing insights in the app such as how their sleep and mood are connected or how their mood or sleep impacts their activity levels. So we’re always working to provide new and valuable health insights for our members.

To that end, we’re kicking off an exciting new project… 8 new insight types in 8 weeks!

Here, we’ll dive into the first of these new insights — sleep debt! Keep an eye out for more insight types coming soon.

What is sleep debt?

At a high level, sleep debt is just a measure of how much you sleep compared to how much you ideally should sleep.

‍There are two kinds of sleep debt:

long term sleep debt that you accumulate over months and years, and
short term sleep debt that you accrue over days and weeks.

Both are important, but the measurement we provide members focuses on short term sleep debt — specifically sleep debt calculated over the last 14 days.

Learn more about sleep debt and the associated risks here.

How Evidation tracks your sleep debt

Here’s the overview of how Evidation calculates sleep debt:

First we estimate your “ideal” nightly sleep duration based on sleep data logged on your sleep tracker. This number is personalized to you, but for almost everyone this number will be between 7 and 9 hours of sleep per night.
We then look at your actual sleep duration over the past 14 days. For each day, we take the difference between your ideal sleep and your actual sleep to calculate a daily sleep debt score.
The daily sleep debt scores are then adjusted to account for the fact that recent sleep debt is more impactful than sleep debt you accrued far in the past. For example, sleeping only 2 hours last night will make you feel terrible today if you’re used to consistently sleeping 8 hours each night, but if you had a night where you slept 2 hours a week ago, it would impact you far less today, assuming the other nights you slept your usual 8 hours.
Finally, we take the adjusted daily sleep debt values and sum them up over the last two weeks. This is your total short term sleep debt.

How do I interpret my sleep debt score?

‍The graph you’ll see in the evidation app shows four different pieces of information:

Your daily sleep duration over the past week
Your ideal sleep duration (the dotted horizontal line)
Your daily sleep debt (the red bars that are stacked on top of your daily sleep duration on days you slept less than your ideal sleep duration)
Your total sleep debt calculated as discussed above (the final red bar)

How do I get my sleep debt score?

In order to receive a sleep debt score you must do the following:

Use a wearable device that logs sleep and connect it to the Evidation platform. Make sure you enable sharing of sleep data when you connect your device.
Wear your device while you sleep as often as possible. In order to receive your sleep debt score, we need at least 10 days of sleep data every two weeks. Too few data points will make our calculations inaccurate.

How often will I get my sleep debt score?

For now, you’ll see your sleep debt score weekly. In the future, we’ll begin updating your sleep score daily so you can better track your score over time. Knowing your sleep debt score makes it possible to take steps to improve your sleep and get the rest you need to feel your best.