Background and Rationale
The month of Ramadan is a critical annual event in the Islamic calendar. Individuals engage in a month-long fasting schedule where meals are taken before sunrise and after sunset, with no water or food intake during the day. The practice leads to not only altered nutritional schedules, but is associated with altered sleeping patterns, characterised by significant reductions in total nighttime sleep, as well as increased daytime nap duration1. In general, poor sleep efficiency is associated with post-meal elevated glycemic responses and sustained sleep restriction might lead to greater subjective hunger and higher caloric intake2,3. Ramadan practising individuals develop strategies to cope with the evolving sleep debt to coordinate with their lifestyles. These could range from staying awake at night and sleeping into mid-day or a planned wakening around dawn meal times (Sahoor/Sehri) and napping after4,5. Physiologically both are likely to impact sleep quality and recovery. Previous studies have captured the impact on sleep using surveys such as the Pittsburgh Sleep Quality Index (PSQI)4. Wearable-based Ramadan health tracking is a very nascent research area with a handful of studies such as Alghamdi et al.,2020, which usually focus on a clinical population5. There is relatively less public literature around productivity impacts in the Ramadan-observing population.
We detected early but striking changes in geographically-restricted patterns within the Ultrahuman Ring AIR user base as referenced in our previous whitepaper6. The lack of sleep information surrounding a largely healthy demographic (Ramadan-observing cohort) propelled us to develop 'Ramadan Mode' on the Ultrahuman application, involving customizations to better suit these sleep pattern changes. This specific mode alters the way sleep index is calculated, which is a reflection of the overall sleep health of a user for the day, by modifying the contributing weightages of sleep epochs in nocturnal time windows and emphasising the value of day time naps. Here we present the general sleep patterns of users who activated this mode and another set that showed distinct activity around the dawn meal times, to track sleep-related behaviours and their impact on sleep metrics during the Ramadan fasting period.
Methods
Aggregate sleep profile data from Ultrahuman Ring AIR users in the GCC region were analysed for a specific signature for the period ranging from two weeks before the onset of the holy Ramadan month (11th March 2024), through the entire month and two weeks after Eid al-Fitr (10th April 2024).
Inclusion criteria involved:
a) Voluntary activation of the Ramadan mode configuration in the Ultrahuman app referred to as RMC group, N=62.
b) We also observed a different group in which individuals who consistently woke up before dawn during the period of Sahoor/Sehri meal and slept after for some period. This group displayed this signature only during the four weeks of Ramadan and not in the weeks before Ramadan onset or after Eid. This group is referred to henceforth as dawn sleep deprivation (DSD) cohort, N=51. DSD Ring AIR users did not activate the Ramadan mode and hence were using unmodified sleep algorithms for all metrics.
Sleep metrics such as total sleep index, sleep duration, sleep heart rate variability (HRV), sleep start, sleep end, movements during sleep and nap duration were collected for the entire eight week period. Data analyses and aggregation is covered under terms of use of the Ultrahuman Ring AIR and application. Data analysts had no contact with any users during the entire study period and worked with de-identified data. Analysis was done in-house using Python-MATLAB modules. All populations were non-normal and we used non-parametric tests for grouped comparisons (pre- and post-comparison). Intermittent ring usage was also observed among users in the study period, and for consistency, such data were not included in week-on-week repeated measures ANOVA analysis.
Result
Ramadan Mode (RMC) sub-group behaviour:
RMC group displayed a dramatic decline of about 10% in sleep index and sleep duration in week 1 as compared to the pre-Ramadan phase (Figure 1, Table 1). Subsequently these metrics showed marginal deviation across the fasting period. The group also showed an appreciable delay in sleep start of about 2 hours, which consistently became later as Ramadan progressed (Figure 2). Interestingly, we observed that HRV did not drop appreciably but there was an increase in movements during sleep sessions (Table 1, Figure 4a and c). Since the Ramadan mode sleep algorithm also included naps after Sahoor, the sleep end times reflected a uniformity across weeks, with an average sleep end time delayed by 2.25 hours (Figure 2). Day time naps did increase by 16% within the first week and remained high throughout (Figure 4b). Two weeks after Eid, most sleep metrics had reverted to pre-Ramadan stages. However this group was still sleeping later than usual by about an hour, and continued to have more movements during sleep (pre vs post Ramadan week).
Figure 1: Graphical representation of median week-on-week sleep index and sleep duration for the RMC cohort. Statistical analysis was performed using repeated measures using the Friedman test.N=37 users who were included wore the ring continuously without any break for the entire study period. Error bars indicate Q1 and Q3 quartile ranges. Please refer to Table 1.
Figure 2: Pictorial layout of sleep start and end times for both RMC and DSD groups. Y axis represents GCC local time in 24h format. N=62 for RMC, N=51 for DSD. Wilcoxon rank sum tests done to evaluate sleep start and end differences between pre-Ramadan and grouped median Ramadan values. p<0.0001 for sleep start and sleep end for both cohorts.
Dawn Sleep Deprivation (DSD) sub-group behaviour:
DSD individuals were tracked independently by sleep disruption around the Sahoor period. We found a substantial and statistically significant decrease in sleep index and fluctuating sleep durations across the next four weeks (Figure 3a and b, Table 1). These individuals did have a significant sleep start delay of over 1.5 hours which extended to 2 hours but did not expand further (Figure 2). Sleep end did not change as much as with the RMC cohort, possibly due to specific work-life commitments but still was statistically significant when compared to pre-Ramadan trends (Figure 2). HRV values were significantly poorer as compared to the RMC group (Figure 4a). Average movements in this sub group was significantly more than the RMC group, with a trend of lesser cumulative nap time (Figure 4 b and c).
Figure 3: Graphical representation of median week-on-week sleep index and sleep duration for the DSD cohort. Statistical analysis was performed using repeated measures using the Friedman test.N=46 users who wore the ring continuously without any break for the entire study period. Error bars indicate Q1 and Q3 quartile ranges. Please refer to Table 1.
Figure 4: Histogram representation of grouped comparison of median non-Ramadan and during Ramadan phase HRV, day time naps and movement. N=62 for RMC, N=51 for DSD. Wilcoxon rank sum tests used for statistical analysis. Comparing within the DSD group, p>0.05 (not significant) for HRV, naps and movement. Comparing within RMC, p<0.05 for naps and movements, p>0.05 (not significant) for HRV. Across group comparisons RMC vs. DSD for Ramadan phase only using Mann-Whitney U test, p<0.05 for HRV, naps and movement. Error bars denote Q1 -Q3 quartile ranges.
Table 1. Repeated measures non parametric analysis for Sleep index and duration
Conclusion and Discussion
This exploratory study was initiated in response to the early changes that we noticed in sleep profiles of Ultrahuman Ring AIR users in the GCC area at the start of this annual event. Ramadan causes drastic changes in physiology; however, most studies are aimed at managing physiological fallouts in individuals with metabolic syndrome or other conditions who are observing Ramadan. There is little information on how a generally healthy individual manages this intense regimen while balancing their usual life commitments. It also serves as a case study for sleep pattern disruption.
We found two overall strategies in individuals- one was to stay awake longer into the night and sleep continuously through early morning up until noon (RMC) and the other was to delay sleep a little, wake during dawn meal time and then sleep again after (DSD). The two strategies did impact overall week on week sleep indices and sleep duration which were picked up by the standard and altered (Ramadan mode) Ultrahuman algorithms. Interestingly HR and HRV did not show as dramatic a difference as movements (tagged to restlessness) did, indicating that autonomic nervous system control in this aspect was maintained. Comparing RMC and DSD we found a significant difference in HRV and movements at the level of weekly averages. Movement during sleep and difficulty sleeping early were being observed in both groups even two weeks after the end of Ramadan, indicating that the body takes a longer period to reset some metrics.
We intentionally kept stringent filtering criteria to identify and track RMC and DSD population, so dataset sizes differ for different analyses. For the week-on-week Friedman test, we only selected individuals with continuous data streams across the entire five weeks. We aggregated more users for before and after comparisons shown in Figure 2-4, since the comparisons were at a group level. In future we hope more users will find value in activating the Ramadan mode, enabling bigger datasets and more powerful analyses of this phenomenon. Ultrahuman remains committed to sharing such insights with its user community and the global audience.
Finally, the impact on a variety of sleep metrics during this month of altered lifestyle using the Ring AIR, lends strong support to the capacity of wearable sensor technology in gathering multi-dimensional, continuous data that can help generate baseline frameworks for largely healthy people. Such normative datasets are the need of the hour to parse out determinants influencing longevity, productivity and wellness, which lend themselves to resilience against diseases later.
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