Sleep loss and circadian misalignment contribute to numerous operational accidents and incidents. The effectiveness of countermeasures and work scheduling designs aimed at mitigating fatigue can be challenging to evaluate in operational environments. This manuscript summarizes an approach for collecting sleep, circadian, fatigue, and performance data in complex operational environments.
It is challenging to collect alertness and performance data in operational environments. Our protocol provides a suite of tools for collection of fatigue countermeasures data in the real world. Our protocol allows for the evaluation of sleep, performance, and the circadian phase in complex operational environments.
These techniques can be used to assess the prevalence of sleep deficiency and circadian misalignment in multiple operational cohorts. These techniques could also better inform longitudinal status of long-term health consequences of chronic sleep loss and circadian misalignment. As the participants are not supervised by research staff, it is critical to fully describe the data collection procedures and to check in frequently with participants.
Before beginning the data collection procedure, select an activity monitor that has been validated against polysomnography in a laboratory environment. Instruct each participant to wear the activity monitor snugly and securely fastened on the wrist of the non dominant hand during the entire experimental period. Activity monitor removals for activities such as swimming or showering should be noted in the daily sleep diary in order to distinguish activity monitor removals from inactivity during naps.
If the activity monitor includes an event marker feature, ask the participant to tap the marker whenever the activity monitor is removed. In order to help us with the analysis. Instruct the participant to press the event marker when going to bed and waking up for every sleep episode to enhance the information obtained in the sleep diary and to assist in the analysis.
After assigning the activity monitor to the participant, select an application to use for the daily data collection. Have the participant complete a baseline questionnaire with demographic information, prior to engaging in any study procedures to aid in the interpretation of the study outcomes. Instruct the participant to complete the sleep diary using the app before and after their main sleep episode.
Upon waking from the main sleep episode have the participant indicate the wake up time, number and duration of awakenings and sleep quality. Instruct the participants to document the durations and timing of any naps and anticipated bed times in the sleep diary just prior to going to bed. For PVT tracking read the following instructions to each participant to ensure that every participant receives the same training.
Please hold the device in the landscape position each time and hover each of your thumbs over the device within a few millimeters of the screen the entire time you are taking the test. During the test tap the screen using the thumb of your dominant hand. That is the hand you typically write with.
As soon as you see the red numbers scrolling in the box you must use your thumb from your dominant hand to respond to the stimuli in all tests. The numbers in the display show how fast you responded each time, the smaller the number the better you did. Try to do your best and get the lowest number you possibly can each time.
If you tap on the screen too early before the numbers appear you will see an error message FS indicating a false start. If you tap using your non dominant arm then you will see the message ERR indicating an error avoid FS and ERR. If you forget to lift your thumb the test screen will remind you after a short time.
Demonstrate the correct position of the touch screen device and the location of the thumb while taking the PVT and instruct the participant to keep the touch screen device in airplane mode with the wifi off at all times. Instruct the participant to initiate the PVT at a time that is free from distractions. If distractions occur have the participant note the number of distractions within the application following the test.
On top of descent of each flight the participant communicates with his working partner to assure that he or she can take time aside to complete the study tasks and that the environment is free of distractions. To measure 6-sulfatoxymelatonin production to estimate the circadian phase provide the participant with a urine kit, urine log and instructions on the training day. The urine kit includes a urinal hat or urinal jug.
Several pipetts, five labeled urine collection tubes per 24 hour collection, two extra tubes and white sticker labels, clean biohazard zip lock bags. Shipping materials, an ice pack, a urine collection log and a copy of instructions for reference during each collection block. Inform the participant to collect all of the urine produced over a 24 hour period starting from the time the participant wakes up for the first urine collection of the day, continuing in four hour blocks throughout the day and an eight hour block overnight for a total of five samples.
To obtain a urine sample instruct the participant to use a new pipett for each sample to transfer a small amount of the urine from the collection container into a new small tube per sample until the tube is at least half full. After capping the participant should label the tube with the number indicating the collection sample of the day. The labeled tube should then be placed into a large zip lock biohazard bag and the bag should be placed into the shipping box with a cold pack.
Then ensure that each participant is provided with a pre paid and pre addressed shipping label. Here an example of an actigram derived from an activity monitor used to track sleep duration, bed time, wake time and sleep quality is shown. For this individual the sleep timing and duration varied significantly as a function of the work start time as assessed by mixed effects regression analysis.
This representative table displays the bedtime, wake time, sleep duration and sleep quality by schedule type as reported by multiple participants in their sleep diaries. The participants went to bed on average at around 23:10 hours on the baseline block, the bedtime for the early duty schedule block differed significantly from baseline with participants reporting earlier bedtimes before early duty start times. The bedtimes for midday and late duty schedules also differed significantly from baseline with the participants reporting later bedtimes.
The participants went to bed significantly later on rest days compared to baseline. Participants obtained significantly less sleep on early starts compared to baseline while the sleep duration on the other schedule types were not different from baseline. 6-Sulatoxymelatonin acro phases for each individual who participated in the urine collection procedures by study block showed that consistent with the findings on sleep the main circadian phase was significantly shifted according to the work start time.
Using mixed effects regression analysis findings were similar for both lapses and response speed on the PVT. Participants showed significant increases in lapses for each schedule type compared to baseline. While participant performances on rest days were similar to baseline.
The most important step in this procedure is the proper training of the participants for completing the study task. Particularly for the PVT data collection. This combination of methods and test ingrained application allows for the collection of sleep, performance and circadian phase data in operational environments.
