How to interpret Sleep Score and Hypnogram

What does your sleep really look like? This article provides tips on how to understand a sleep analysis including an explanation of the hypnogram to give you a better comprehension of your sleep pattern.

Many of our customers, Sleep Enthusiasts just like you, are asking us if we can assist in analyzing their sleep for them. While we unfortunately cannot provide this service, we surely can teach you a thing or two about how you can analyze your sleep with the help of Somnofy. This article aims to explain the setup of our daily sleep analyzes such that you can, with a little exercise, interpret your own results after just a couple of nights. 

It is important to note that this is not medical advice. Contact your physician if you are having trouble with your sleep.

The first example shows an actually measured good night’s sleep of a female person, age 20. 

Sleep Score

The first «block» you see when opening your Somnofy app is the Sleep Details main screen. Here, you can see three quantitative sleep values on the top:

  • The time point you fell asleep
  • Your total sleep time
  • The time point you woke up

The Sleep Score is placed prominently in the center and displays a point score between 0-100. The higher your sleep score, the closer to optimal was your sleep.

You can compare different nights with each other by taking a quick look at the sleep score. 

Two more values are placed right under the Sleep Score: 

  • Sleep Efficiency
  • Respiration Rate

The Sleep Efficiency is a percentage value arrived at by dividing the time spent in bed by the time actually asleep. Thus, the closer to 100%, the better. Everything above 90% is excellent.         A low value points towards a lot of time in bed spent awake.

Sleep Stages Distributions

The colorful pie chart shows the distribution of four different sleep phases across the sleep session:

  • Awake (red): Should ideally be as low as possible.
  • Light (light blue): Light sleep stage. Typically  ~ 50 % of any sleep session.
  • Deep (dark blue): Deep sleep stage. Typically ~ 20 - 25 % of any sleep session.
  • REM (yellow): Rapid Eye Movement sleep stage. Typically ~ 20 - 25 % of any sleep session. 
  • No presence (grey): Somnofy did not detect your presence. Can be a toilet visit.

Learn more about the different sleep stages in this article about what sleep is.


 The further you scroll down, the more detailed the sleep analysis gets. The values depicted in this picture include:

  • Your intended sleep time
  • Total time spent in bed
  • Your sleep onset (from intended sleep to fell asleep)
  • Your times awake/away

Somnofy has a number of  sensors that measures your sleep environment parameters such as room temperature, air humidity, air quality, ambient light, air pressure and sound level. This gives you the opportunity to look for patterns and explanations on your own.

The Hypnogram

This is where the sleep analysis gets a bit difficult without some experience. The hypnogram is essentially a timeline of your sleep. It shows at what time you have been in which sleep stage. The colors represent the above mentioned sleep stages from the pie chart. 

Everyone starts Awake after going to bed, so you will always find a red bar at the start of each hypnogram. The broader this bar, the longer it took you to fall asleep. Light blue follows with you falling into Light Sleep before sinking deeper into the dark blue Deep Sleep phase. In this specific example we see — as is normal for most people — short red bars that signify short Awakenings, in this case so short, that the person won’t remember most of them the next morning. They are enough to interrupt the Deep Sleep phase that person was in, though. This happens several times throughout the night.

The yellow bars are bouts of REM Sleep or dream sleep as some people like to refer to it. It is typical for REM Sleep to be more prominent later throughout the night. As you can see in the above picture, more Deep Sleep happens towards the early night, while more REM Sleep can be found towards the later night. This also means that you effectively deprive yourself of REM Sleep if you wake up earlier than your body needs. 

Let’s continue with more details.

And some other graphs

Right below the hypnogram, you can find more graphs respectively depicting:

  • Movement: black bars that show movement. The higher the bar, the more movement in any specific 30s interval.
  • Respiration Rate: This is your breathing rate in breaths/minute. If the graph disappears sometimes, this is due to large movement in that time period which makes it hard for Somnofy to isolate your breathing movements.
  • Distance: The distance graph shows your distance to the Somnofy unit.
  • Sound: The sound level in decibel. This is not a “recording”, just information of how loud it was during a night. 30dBA is practically silent.
  • Ambient Light: This graph shows light sources in the bed room. You can see two small spikes that could be a night lamp, or a phone screen being turned on.


The above example is a good night’s sleep for a young girl, 20 years of age. It is on the longer end with a total sleep time of over 9 hours. She had a couple of awakenings during the night, but probably remembers very few of them. One reason could be the air quality in her room and the temperature of over 20 degrees Celsius. One recommendation for her could be to have her open the bedroom window during the night.

One example of a bad night

The above example included a good night’s sleep for illustration purposes. The following sleep analysis includes a bad night for this same person as above. In fact, the below analysis has been taken just one night after the above analysis, which lets us get a closer look at how one night may influence the next.

We need to make clear that bad nights can happen to everyone and for a variety of different reasons. This specific example is only meant to be an illustration of how a bad night could look like.

This is not medical advice. Any possible reasons are pure speculations, simply based on personal experience with sleep analyses.

The Obvious

Quite easy to see: the sleep score is markedly lower than in our above example, also signified by the red color, instead of green, as above.

Our person fell asleep at 1:02 am and slept very short this night, with under 6 hours of sleep, before having to get up at 7:03 am.

In addition, we can see a non-optimal sleep efficiency of 67 %, which might point to her having spent a lot of time awake in bed. 

The respiration rate is very similar to last night’s analysis and therefore does not point to any immediate physical reasons for why this night should be so much shorter than the previous.

Let’s look a bit further.

More details

The pie chart does not give us much information, apart from the fairly short Awake section of the circle. This does not look as if our person was awake a lot after having fallen asleep.

First the Details section provides us with some clues on what has happened. Our example person has spent 8 hours and 24 minutes in bed, but only 5 hours and 40 minutes of those asleep. The sleep onset time of 2 hours and 23 minutes finally explains what is going on: After going to bed, trying to fall asleep from 10:39 pm, it took her more than 2 hours to actually fall asleep.

Let us take a closer look at the hypnogram to confirm our theory.

The Hypnogram shows it

The inevitable large red area proves us right: a long time to actually fall asleep, cuts the effective sleep time short during this specific night.

We see a lot of movement, where this person probably rolls around in bed trying to find a comfortable sleeping position. 

Then finally, she falls into a deep sleep phase, and with a couple of short awakenings, and definitely lacking some REM sleep stages in the end, she has to get up to the sound of the alarm, which calls her to get up, without remorse.

Another summary

We have been looking at two consecutive nights of a 20 year old female which shows one night of good quality sleep — probably a bit too long — followed by an example of a rather bad night with a painstakingly long sleep onset time, lying awake, waiting for sleep to come.

The tip for this person is as follows:

  1. Have a regular sleep schedule. Aim to go to bed at the same time each day to prevent such large variation in sleep quality.
  2. Get up out of bed, if you are not able to catch sleep after trying for about 20 minutes. Get out of bed and do some calm activity. Sit on the sofa an read a book, write a diary entry, or listen to some soothing music.
  3. Open your window to improve air quality is possible.

And read this article about how to improve your sleep.