Sleep

FAQs

What are sleep stages?

During a sleep session, your body repeatedly cycles through light, deep and REM (rapid eye movement) sleep, as well as short periods awake which you might not even be aware of. Depending on the duration of the sleep session, you will move through up to five sleep cycles, each lasting about 90 minutes on average. Each cycle usually starts with light sleep, followed by deep sleep, REM sleep, and ends with a brief period awake. However, sleep cycles are not necessarily all the same; the early part of your night consists of more deep sleep and the later part more REM sleep. Your transitions between sleep stages and time spent in each of the sleep stages are visualized in a hypnogram in the app.

Why are the sleep stages important?

The duration and distribution of each sleep stage may reveal important information about a person’s mental and physical well-being. For example, individuals with depression characteristically demonstrate reduced deep sleep and increased REM sleep. Deep and REM sleep are particularly important in consolidating memories and play a role in cognitive performance. Research suggests that deep sleep is also involved in repairing damaged tissues and restoring energy sources.

What happens in each sleep stage?

• Light sleep: During light sleep, your brain transitions from wakefulness to sleep. Your breathing and heart rate become regular and your body temperature drops. During this stage, you are somewhat alert and can easily be woken.

• Deep sleep: In deep sleep, your body is less responsive to your surroundings. Your breathing slows down and your muscles are more relaxed. It is more difficult to wake up during this stage. This is when most of your body’s muscle and tissue repair takes place, growth and development are stimulated, immune function is boosted, and energy is restored for the next day.

• REM sleep: While you are in REM sleep, your eyes move rapidly in various directions and your body is relaxed and immobile. Most dreams occur during REM sleep. This stage is thought to be important for learning and memory, since this is when your brain consolidates and processes information gathered while you were awake so that it can be stored in your long-term memory.

• Awake: An awakening of more than five minutes is classified as awake, and is not included in your total sleep time. 

How much sleep do I need?

How much sleep you need depends on your age. The National Sleep Foundation gives the following guidelines per age group:

• Teenagers (14 - 17 years):  8 - 10 hours

• Younger adults (18 - 25 years): 7 - 9 hours

• Adults (26 - 64 years): 7 - 9 hours

• Older adults (65+ years): 7 - 8 hours

Where can I view my sleep stages?

Sleep stages are displayed in a hypnogram in the app.

What is unclassified sleep?

During sleep, if you lie on your arms, restricting blood flow, or the position of your device changes and the sensor picks up too much ambient light, logged data may be low in quality. Low data collected on the device during this time won’t be used to classify sleep into stages. This is to ensure that sleep classifications which are made, are made on valid and accurate data.

Can the sleep information displayed in the app tell me if I have sleep apnea or any other sleep disorder?

The app cannot be used to diagnose sleep disorders or to classify individuals as ill. We recommend that you seek professional advice if you are concerned about your sleep health.

What does my sleep score mean?

Your sleep score is a measure of your overall sleep health, with a higher percentage indicating better overall sleep health. The score is derived from your aggregated nighttime sleep data over a set period of time. You can expect to see your sleep score after at least seven days’ worth of adequate sleep data has been uploaded.

Why is my sleep score important? 

Getting sufficient sleep is essential to your body’s development and repair functions, as well as for memory consolidation. It protects against diabetes, some cancers, heart disease, and some psychiatric diseases. The amount and quality of sleep you get therefore has a big impact on your health. While scientific literature strongly supports the existence of a relationship between sleep and long-term health, little information exists about how the various individual elements of sleep (such as duration, schedule, awakenings, movements and time spent in each sleep stage) affect health. The sleep score takes all of these individual elements of sleep, as well as the relationships between them, into account to provide an easily interpretable measure of your overall sleep health.  

When will I see my sleep score?

You can expect to see your sleep score after at least seven (not necessarily consecutive) nights’ worth of adequate sleep data has been uploaded. When there is a large portion of a sleep session which goes unclassified (see description above), these sessions do not contribute to the calculation of the sleep score. This is intended to maintain the accuracy of the score. The longer and more consistently you wear your device, the more accurate your score will be. The score uses a 30-day rolling window to provide a more reliable view of your long-term sleep health. 

You may see improvements in your sleep score as your mental and physical well-being, stress levels and sleep hygiene improve. It may take a few weeks before these improvements are reflected in your score.

How is my sleep score calculated?

In order for your sleep score to be calculated, a minimum of seven (not necessarily consecutive) nights’ worth of valid sleep data has to be uploaded. The longer and more consistently you wear your device, the more accurate your score will be. The score uses a 30-day rolling window to provide a more reliable view of your long-term sleep health. 

How can I improve my sleep score?

• The less interrupted your sleep is, the better your sleep quality will be.

• Get into the habit of starting your sleep routine in the same way at the same time each night.

• Practice good sleep hygiene by eliminating habits that can contribute to poor sleep quality, for example:

  • Avoid excessive caffeine consumption before trying to go to sleep.

  • Avoid exposure to light in bed before trying to go to sleep.

  • Minimize your alcohol intake: the fewer alcoholic drinks, and the further away from your bedtime, the better. 

  • Always prioritize your regular bedtime over work and other activities. 

  • Switch off the TV and any other electronic screens an hour before bedtime.

  • Keep your sleep environment free of any stimuli that might keep you awake, including mobile devices, TVs and radios.

Please be aware that it may take a few weeks before improvements are reflected in your score.

Why did my sleep score suddenly decrease?

If your sleep routine significantly changes, you may see a decrease in your sleep score. Disruptions could include travelling to a different time zone, acute illness, or taking naps. Since your score is calculated over a 30-day rolling window, these changes will affect your sleep score for up to 30 days. 

What is a valid sleep session?

• A valid sleep session must have a total sleep time of at least three hours.
  
  

What limitations apply to the sleep score?

Three types of limitations apply to the sleep score:

• Limitations on sleep sessions included in the sleep score:

  • The sleep score is limited to sleep sessions where:

    • The total sleep time is at least three hours

    • The sleep session had sufficient classified sleep

  • Regarding what constitutes a sleep session, the session starts when you fall asleep and ends when you wake up and do not sleep any further. 

  • A sleep session may include short periods of wakefulness.

  • If there are periods during the night where the device signal quality is too poor to record sleep, the entire sleep session will be excluded from the calculation of the score.

• Limitations on individuals:

  • Individuals who fall outside the age range of 18 - 70 will not see a sleep score.

• Limitations on the validation and use of the sleep score:

  • The app cannot be used to diagnose sleep disorders or to classify individuals as ill. We recommend that you seek professional advice if you are concerned about your sleep health.

Troubleshooting

User reports missing sleep session

Checks:

• Did the user wear the device while sleeping?

• Has the user performed a successful upload?

• Ask the user to perform another upload.

  • If the user’s device and mobile has their Bluetooth on and are connected, the app syncs data in the background at least every 2 hours. Users can also manually force a data upload when opening the app and pulling the homepage down to force a sync and reload.

  • Ask the user to confirm whether their sleep is now displayed.

• Was the device fitted securely?

  • If there were periods during the night where the device signal quality was too poor, sleep may not have been recorded.

  • The device must not be so loose that it moves around a lot, nor must it be so tight that it restricts blood flow.

  • It is best to fit the device above the wrist bone.

  • The user may have slept in a position that prevented the device from making contact with their skin. 

• Did the device battery run out during the night?

• Did the user sleep for at least three hours?

• Did the user have a very short/very long sleep session?

  • The model does not process sleep sessions that last less than three hours or more than 14 hours and 12 minutes,  because it is not validated for those time lengths.
    
    

User reports two separate sleep sessions for the previous night

Checks:

• Was the user’s sleep session interrupted?

  • When an awake period of two hours or more is detected within a sleep session, that sleep session is split into two separate sessions.

User reports a partially missing sleep session

Checks:

• Did the user sleep for less than three hours either before or after an interruption in their sleep session? 

  • When an awake period of two hours or more is detected within a sleep session, that sleep session is split into two separate sessions. However, if one of those two sessions lasts less than three hours, it will not be displayed in the app.

User reports missing sleep score 

Checks:

•  Has the user uploaded at least seven nights’ worth of valid sleep data?

  • In order for a sleep score to be calculated, a minimum of seven (not necessarily consecutive) nights’ worth of valid sleep data has to be uploaded. The longer and more consistently the user wears their device, the more accurate their score will be. The sleep score uses a 30-day rolling window to provide a more reliable view of long-term sleep health. 

• Did the user have a valid sleep session?

User reports a sleep score that is too high compared to how they felt they slept

Checks:

• Does the user suspect that they may have a sleep disorder, such as sleep apnea, or other health issues that may be affecting their sleep quality?

  • The app cannot be used to diagnose sleep disorders or to classify users as ill. Advise the user to seek professional advice if they are concerned about their sleep health.

• Does the user have a combination of very high-scoring inputs (good) and very low-scoring inputs (bad)?

  • Due to the linearity of the sleep score model, having one high-scoring input and one extremely low-scoring input could cancel each other out, resulting in an average sleep score.

User reports a sleep score that is too low compared to how they felt they slept

Checks:

• Does the user suspect that they may have a sleep disorder, such as sleep apnea, or other health issues that may be affecting their sleep quality?

  • The app cannot be used to diagnose sleep disorders or to classify users as ill. Advise the user to seek professional advice if they are concerned about their sleep health.

• Does the user have a combination of very high-scoring inputs (good) and very low-scoring inputs (bad)?

  • Due to the linearity of the sleep score model, having one high-scoring input and one extremely low-scoring input could cancel each other out, resulting in an average sleep score.

User queries whether they might have a sleep disorder, based on their sleep data

• The app cannot be used to diagnose sleep disorders or to classify users as ill. Advise the user to seek professional advice if they are concerned about their sleep health.