What You’ll Learn in This Article
- What you can learn from your night-time heart rate
- What typical patterns you can see in your night-time heart rate curve
- What changes you can make to your lifestyle and how they affect your heart rate while sleeping
Your Heart Rate During the Night Reflects the Day
The Oura ring tracks your night-time heart rate continuously during the night with infrared LED sensors. In the Oura app, you can see it in 5-minute sections. When looking at the heart rate curve in the Oura app, pay special attention to these three things:
- What happens to your heart rate after you fall asleep: does it go up, down or stay level?
- When does your heart rate reach its lowest point (the nadir): early, mid or late during the night?
- What happens to your heart rate right before you wake up: does it go up, stay level or go down?
With these three questions in mind, here are three patterns you may recognize in your own nocturnal heart rate curve.
The Hammock: Relaxed in Bed. Ready To Rise.
The hammock-shaped curve can be considered the optimal heart rate curve. During the first sleep cycles, your body relaxes and your blood pressure and heart rate drop. Your lowest heart rate happens at the midpoint of sleep when the amount of melatonin is at its highest. If you are perfectly aligned with the rhythm of the sun, your lowest basal body temperature also occurs around 4 am.
Note that your heart rate can momentarily rise during REM sleep. You can ignore these spikes when looking for the hammock-shaped curve.
Towards the end of the night, your heart rate starts to rise to prepare you to wake up. The hammock curve is a sign that your body was relaxed during the night, and ready to rise after a good night’s rest.
The Downward Slope is a sign that your metabolism is working overtime. Did you have a late meal, a late workout or a glass of wine before bed? If your resting heart rate starts high and reaches its lowest point right before you woke up, you may wake up feeling unrefreshed.
If you see the downward slope regularly, it’s a good time to stop and think if there’s something you could do differently. If you are a late exerciser, doing your physical training session 1–2 hours earlier can be a significant change, for example.
If your heart rate goes up right after you fall asleep, it may be sign that you’re too tired for bed. If it’s past your regular bedtime, you may start feeling the effects of your increased melatonin and lowered blood pressure as your body is trying to inform you about bedtime passing.
Perhaps you went to bed at a different time than usually? Also staying in bed later than normally reportedly leads to lowered cognitive performance the following day. Keeping a steady sleep routine really helps you get better sleep and perform better during the day.
There is no single cause for why heart rate starts to increase at the start of the night, but there are some likely candidates: when you relax during the sleep, your airways may actually inhibit the airflow to your lungs. It can also be a sign of your sensitivity to some foods and nutrients. An elevated heart rate may be linked to elevated blood pressure and a decrease in the restorativeness of your sleep.
3 Things to Try
- Try sticking to a steady sleep schedule: wake up at the same time during the week but also on the weekends.
- Pay attention to your meal timing: late meals may show up as the Downward Slope.
- If you see the optimal Hammock, work backwards to find out why: What did you do the previous day? What didn’t you do? The ability to add notes in the Oura app will help you see what lead to the preferable Hammock heart rate curve.