Background

Sleep is important for humans in maintaining normal physical and mental health, as well as keeping good performance and productivity. Sufficient sleep duration and quality sleep constitute the definition of good sleep (Caldwell et al., 2020; Flynn-Evans et al., 2016; Wu et al., 2018). The body’s innate 24-hour biological clock, called the circadian rhythm, regulates the cycle between wakefulness and sleepiness and is affected by the amount of light the eyes receive. The abundance of light during the day contributes to the normal alertness humans experience during late morning leading up to the afternoon, and the lack of light during sunset to late evening is a signal to the suprachiasmatic nuclei to release sleep-inducing hormones like melatonin (Space Center Houston, 2019; Wellcome Trust, 2013).

Sleep problems occur when disruptions to the rhythm occur. Humans experience jet lag because of the circadian misalignment to the new local time zone. For astronauts, light cycle changes are more extreme due to the fact that in space, they experience sunrise or sunset every 45 minutes. Work hours that are not aligned with an individual’s circadian rhythm can also cause disruption. These sleeping problems can lead to sleep deprivation which can further lead to fatigue which can compromise a person’s health and overall performance (Caldwell et al., 2020; Flynn-Evans et al., 2016; Wu et al., 2018).

Various countermeasures are present in the form of medication, exercises, food intake, and simple tools that can simulate the correct environment appropriate for an individual’s circadian rhythm (Advanced Concepts Team, 2017; Baskin, 2020; Howard & Rainey, 2017; Smith et al., 2014; Wu et al., 2018). Sleep shift schedules are also used to prepare individuals for a new sleeping schedule they can follow in order to reduce the effects of abrupt changes in the environment that can further affect their circadian rhythm (Stewart, 2018). These countermeasures are effective on their own rights and can be used to alleviate both fatigue and sleeping problems. 

Goals

By designing this app, we hope to help not just astronauts, but also people who regularly travel internationally from one time zone to another. We would also like to help the people who have circadian misalignment due to various reasons such as their differences in work shift.

We are aiming to build the foundation of our envisioned working application during the hackathon. Through the development of the design and functions of this tool, snippets of code, and the overall flow of the application, we are hoping that Aurora will be a good start for the problems we are trying to solve. 

How The Application Works

Upon application entry, the user will be asked to log in or sign up. For astronauts, the database containing their personal and medical information is already linked to the application. They simply have to log in with their username and password. For regular people who are international travellers or shift workers, they have to input their username, name and password (optional: weight, height, birth date).

The user will be asked to input their flight details: the date, time, and airports of both departure and arrival. A database of airports will be available in the application, so the user can select the airport by searching its name or location. Using the latitude and longitude, the time zones of the two airports will be obtained, along with the number of days until the flight. With this data, the time difference in the user’s scheduled bedtimes will be generated. 

In addition, the user will be asked questions regarding their sleeping habits. Sample questions include:

1. What time do you usually sleep?
2. Do you take naps? If so, what time?
3. Do you have difficulty sleeping?
4. What tools do you use to induce sleep? (i.e. sleeping pills, mask, earplugs, etc.)
5. Occupation? 
6. Current work period? [Additional question (Optional): Are you shifting to a different work period]

After filling out the needed information, the application will direct the user to an overview of the proposed activities within the next 12 hours that will help them in sleep schedule shifting. This will be shown through a clock which is divided into parts that show the upcoming activities. The app considers proper eating and exercising habits which will ensure alignment with the recommended sleep schedule, given that there should be ample time between meals and sleeping time. 

Other Features

The user may also opt to add their own tasks or hobbies to the schedule. Tasks can be assigned as either essential or non-essential in order to further aid schedule adjustments. For astronauts, their tasks (i.e. spacewalks) are already synced to their accounts so there is no need to enter it manually. They may, however, add more tasks into their schedule.

Throughout the day, the application will notify the user regarding upcoming activities and their respective durations. The user will also be asked if they were able to follow the recommended schedule. If not, the schedule will automatically be adjusted to accommodate these delays. After every essential activity, the app will also ask the user whether they have done the task, have skipped the task, or are currently doing the task. Unfinished activities will automatically result in the adjustment of succeeding tasks. 

In order to implement sleep shifting more efficiently, a built-in alarm will be included. At the user's supposed wake up time, the alarm will ring continuously in between intervals until the user responds to the pop-up form regarding their sleep quality. The pop-up form will contain questions about the user’s sleep, such as the quality of their sleep and a rough estimate of their sleeping time. The data collected will be used to further personalize the recommended sleep schedule. This will also allow the app to generate possible countermeasures for sleep problems and other issues.

In cases of sleep deprivation, the app will generate nap times for the user. If ever the schedule is full, the app will give a prompt asking if the user prefers to remove or reduce the duration of a non-essential activity in order to accommodate nap times with corresponding alarms. The schedule will also adjust these non-essential tasks in situations where the user was not able to eat during the designated eating period. However, the application will not schedule new eating periods 3 hours before the main sleeping period and nap times 5 hours before the main sleeping period as this can affect the circadian rhythm of the user.

Another feature that is exclusively for the use of astronauts is the logging and tracking of foods and nutrition. Using the database of food choices in the application, astronauts can simply select the food they eat for a specific eating period. The nutritional facts of the selected food will automatically be added to the progress bar of the user for the day. The progress bar will help track the user's intake compared to the recommended intake which they must fulfil each day.

Other Factors to Consider

Given a large time difference, the user's sleep schedule does not shift entirely to adjust to the destined location. The schedule shifts ±20 minutes for a gradual adjustment, which changes everyday with a maximum of 3 hours of total shift. This allows users to shift their sleep without having an impractical schedule. 

Given that astronauts at the International Space Station follow the Prime Meridian time zone (GMT+0), they would have to re-adjust their sleeping schedule again after docking. Also, the shifts at the mission control center and overall work schedule should be considered as it may affect their proposed sleeping schedule for some days. This can also apply to some people who have unexpected flights, night shifts, or overtimes at work. If this problem occurs, the user may add their task or flight and/or change their sleeping period for the day, and the application will propose a new schedule. This newly generated schedule contains longer naps or short sleeping periods, as well as countermeasures that will help prevent the user from experiencing fatigue. This schedule must also not drastically affect the next day’s schedule to prevent the desynchronization or misalignment of the user’s body clock. A sample adjustment would be the shifting of the sleeping period earlier by three hours to account for the sleep lost the previous day.