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Get to know SleepTank

    • The first thing the user should do when using SleepTank is set the sleep goal in the profile.

    • Everyone has a specific amount of sleep needed to be fully rested and alert.

    • In addition, wearables differ in how selective they are in removing disturbances from your total sleep time. 

    • Start with a goal of 8 hours. To calibrate your goal, look at the amount of sleep the wearable gave you credit for after a good restful night of sleep. You may have been in bed for 8 hours but the wearable scored it as 7.5 hours after subtracting for disturbances. If you feel it was a good night for you, then set your goal to 7 hr 30 min.  

    • If over time, you always exceed your goal, then decrease it to represent your usual good night of sleep. If you never hit the goal even after a great night of sleep, then reduce your goal.

    • You can rebuild your SleepTank after you change your goal to reflect your true state.

  • The objective is to get enough sleep each day to raise the SleepTank level to about 100%.

    • The low fuel warning light on a car's dashboard indicates that it is time to refuel.  Sleep fuels your ability to think, make decisions, and react quickly. A lack of sleep results in fatigue and cognitive impairment, or the inability to think clearly.

    • SleepTank™ provides you with warnings about your fatigue level at three different times during the day. Changing your sleep goal will affect when the warnings occur. Examples below are based on the default user with an 8-hour sleep goal.

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    1)   Bedtime: Time to refuel. Go to sleep now to avoid cognitive impairment.
    This warning will occur at the end of a normal day awake. This is about 16 hours of wakefulness (16 hours awake + 8 hours asleep = 24 hours) for a user with an 8-hour sleep goal. The SleepTank™ will be depleted to about 33% and the user is approaching a normal bedtime. Going to sleep at this time will prevent fatigue.  Alertness after this point begins to degrade due to sleep loss.

    2)  Warning: Start of cognitive impairment due to lack of sleep.

    This warning will occur when cognitive impairment due to fatigue begins to mimic cognitive impairment like the effects of having a blood alcohol concentration (BAC) of 0.05. This is about 18.5 hours of wakefulness for a user with an 8-hour sleep goal. The SleepTank™ is depleted to about 22%. Go to sleep now to avoid severe fatigue.

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    3) Empty: Running on fumes. Severe cognitive impairment due to extreme lack of sleep.

    This warning will occur when the SleepTank™ level reaches 0% and sleep debt is equivalent to 24 hours of continued wakefulness. The SleepTank™ will reach 0% in less than 24 hours if you have not slept enough over several days. Adding a small amount of fuel will not refill the tank. Cognitive impairment will be like the effects of a BAC higher than 0.08. Go to sleep now to alleviate the effects of severe fatigue.

    • There are two reasons that SleepTank does not need a circadian function. 

    • First, in a population based model that estimates sleep, like SAFTE-FAST, the circadian rhythm is needed to modulate sleep quality. SleepTank doesn't need that because sleep quality is represented in the sleep recordings from the wearable. 

    • Second, SleepTank is designed to focus on factors a person can control, that is, sleep and sleep debt. Adding a circadian function would mask this factor and make it more difficult to see latent sleep debt that can impair alertness in the future.

    • Currently, it will accept sleep data from any Fitbit, Garmin, and Oura devices.

    • These were selected for accuracy, battery life, affordability, and ability to edit and add sleep records.

    • SleepTank was designed to be device agnostic.  We use a device integrator, Terra, and can add other wearables based on user survey of preferences.

    • Apple watch is popular but is limited for sleep studies because of the battery life.

    • Fitbit and Oura devices have been evaluated against laboratory measures of sleep and field measures and found generally to be as accurate at sleep-wake detection as a research actigraph (Chinoy et al. 2021, Chinoy et al. 2022).

    • Error rates in sleep-wake detection (compared to PSG) from Fitbits, Oura, and Garmin are also within acceptable limits for use in FRMS (Reifman et al. 2023). IBR is happy to collaborate with company for any evaluation of a target wearable compared to laboratory/PSG or field measures of sleep.

    • No explicit requirement for a specific actigraph.  Data must be trustworthy and validated for purpose.  At this time, no company has asked the FAA if commercial wearables can be used for sleep measurements for a safety case.

    • Other regulators accept commercial wearables for documentation of a safety case.

    • With Fitbits or Garmin devices, you can manually enter the missed sleep, and you will get credit for it. Oura does not allow manual entry of a sleep record.

    • In SleepTank, use the Rebuild feature to recalculate your SleepTank score.

    • Yes, these devices detect naps.  The minimum nap duration varies by device.

    • Fitbits look for sleep longer than 1 hour.

    • Garmin devices have no specific minimum nap duration and a 3 hour maximum.

    • Oura rings detect naps longer than 15 minutes and shorter than 3 hours.

    • With Fitbits or Garmins, you can add a sleep record or edit a record.  If the device determines that your activity was consistent with sleep, it will give you credit.

    • In SleepTank, use the Rebuild feature to recalculate your SleepTank score.

    • The ability to adjust for time zones depends on the wearable software.  We have designed the SleepTank backend to account for changes in time zones.

    • It is best practice to sync the wearable to local time before and after each sleep event to make sure time zones are consistent.

    • If there appears to be an error, use the Rebuild function to attempt to correct the SleepTank history.

    • Any large gap in sleep history will be a problem because SleepTank will decrease to zero. When that happens, the person will have to delete their account and start over with a fresh tank.

    • If the interruption was short, the user can manually add the missed sleep and rebuild the SleepTank (Fitbit and Garmin).

    • At this juncture, access to SleepTank will be paid for by the company and the user will get a company code to access the app.

    • The company will have to enter your email address into an “allowed user” database.

    • We expect that for personal sleep hygiene applications, the person will provide their own device.  SleepTank provides added value at no added cost to the user.

    • Commercial wearables are simpler, smarter, cost effective, and logistically convenient.

    • IBR has conducted a pilot wearable acceptance survey.  Results indicated that pilots were willing to share data if devices were provided by the company.

    • For company sponsored data collections, the company can provide inexpensive devices, such as Fitbit Inspire 3.  They have been validated as accurate.

  • Data collected through SleepTank is privacy-protected in line with General Data Protection Regulation (GDPR).
    Basic data rights from GDPR:

    ·   Confirm the existence of data

    ·   Access own data

    ·   Correct data

    ·   Anonymize, block, or delete data

    ·   Move data

    ·   Know who has seen data

    ·   Deny consent

    ·   Revoke consent

    For a study, users could opt in to data collection. No names or identifying information is downloaded from SleepTank. Data is delivered to IBR, not directly to the company. IBR can provide a group view of employee sleep behavior to the company, but the company would not be able to link a specific person to sleep behavior without the person’s consent and assistance.

    • Your data are anonymous and cannot be accessed by the company.

    • However, your legal right to delete your data after a mishap is a personal decision.

    • Your sleep history is an important factor in whether you are fatigued.  A record of insufficient sleep is a factor.

    • Your SleepTank score is not a substitute for your own personal assessment of fatigue.  Your fitness should rest on your personal assessment, not on specific scores from SleepTank. 

    • It is the person’s responsibility to make optimal use of sleep opportunities. SleepTank provides feedback and planning aids to facilitate adequate sleep in preparation for duty.

    • Whether you have had enough sleep is a shared responsibility: actual sleep depends on sleep opportunities and the person’s decisions to use those opportunities.  Determining responsibility in a particular circumstance is beyond what SleepTank can do.

    • Our model is based on a corporate subscription that makes the App free to the end users.  The subscription would extend to all employees authorized by the company.

    • The company cost is based on the total number of end users. Our current target price is based on the number of persons expected to use SleepTank. For a launch customer, we are happy to offer a much reduced rate provided we can publicize the engagement and conduct surveys to assess and improve the service.

    • Yes, SleepTank is designed for sponsoring companies to collect deidentified data for sleep studies, provided the individual user agrees to share their sleep data.

    • Privacy protection is inherent in the data collection process.  When used for data collection, IBR will serve as the third-party intermediary to protect the anonymity of the pilot.

    • SleepTank used for data collection can be set to show the full features of SleepTank or to not show the SleepTank score as a control group.

    • At the conclusion of the study, IBR can download the sleep data and share de-identified results.

    • The SleepTank model is similar to the sleep reservoir in SAFTE-FAST, but not identical because it is tailored to the sleep needs of the person and is scaled to reach zero after being awake 24 hours. 

    • But for an eight-hour person, the critical time indication in SleepTank is about the same as a 77% effectiveness and 80.5% reservoir for a fully rested person awake for 18.5 hours.

    • When the SleepTank reaches zero, that is roughly equal to a 70% effectiveness and a reservoir of 75%, assuming no prior sleep debt and staying awake for 24 hrs.

    • Yes, we can export a csv file and use it as input to SAFTE-FAST.

    • Just remember that the SAFTE-FAST model assumes an 8-hour sleep need, so a person with a 7-hour sleep goal consistently waking with a SleepTank at 100% will be shown as sleep deprived in SAFTE-FAST relative to the 8-hour goal.

    • When SleepTank data are used as input to SAFTE-FAST, the sleep should be aggregated across a population to get a reasonably good estimate of average effectiveness.

    • Similar to the Zulu watch, SleepTank data can be used for harmonizer studies.  Compared to the Zulu watch, data collection is simpler because the devices send data to the cloud for download at the end of the study.  That process would be built into the IBR harmonizer project.

    • When SleepTank is used for data collection, there is a small one time fee to set up the groups and pull the data. If used for a harmonizer study, the fees for analysis are similar to what is charged using the Zulu watch.

    • The company saves on the costs of distributing hardware, collecting the hardware, and transferring the data manually.

    • The cost of SleepTank does not include the cost of the wearable.

  •  www.sleeptank.org or Contact Murray McGrath mmcgrath@saftefast.com

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