Overnight on-call schedules can impact sleep, wellbeing, and alertness, which can be detrimental on the performance, physical and mental health of residents. Moreover, rotating shift work may have a long-term negative health impact (e.g. increased risk of diabetes). Within the National University Hospital (NUH), two different systems of rotating on-call schedules are implemented. In the night float system, residents work from 8 pm to 8 am for 5 - 7 consecutive nights once every month, compared to the traditional overnight on-call system, where each resident is on call for 4-6 nights per month (7 am - 5 pm, followed by overnight call until 8 am the next morning). The aim of the current study is to track sleep, wellbeing, and glucose metabolism during the different phases of the night float and traditional on-call schedules.

Overnight on-call schedules can impact sleep, wellbeing, and alertness, which can be detrimental on the performance, physical and mental health of residents. Moreover, rotating shift work may have a long-term negative health impact (e.g. increased risk of diabetes). Within the National University Hospital (NUH), two different systems of rotating on-call schedules are implemented. In the night float system, residents work from 8 pm to 8 am for 5 - 7 consecutive nights once every month, compared to the traditional overnight on-call system, where each resident is on call for 4-6 nights per month (7 am - 5 pm, followed by overnight call until 8 am the next morning). The aim of the current study is to track sleep, wellbeing, and glucose metabolism during the different phases of the night float and traditional on-call schedules.

The availability of accurate mobile methodologies to monitor sleep and metabolic health provide new avenues for the improvement of sleep health and well-being. Wearable sleep tracking devices and smartphone apps provide remarkable opportunities for non-invasive, longitudinal sleep detection. Measurement of sleep during different stages of the shift schedule (baseline, on-call, recovery) can provide detailed insights into the temporal impact of the different schedules. Moreover, self-reported ratings of sleep quality, wellbeing, and time-use (delivered through phone-based e-diary methods) can further detail the mental health impact associated with these schedules.

Wearable continuous glucose monitoring systems (CGMS) provide a minimally invasive means of passively tracking ambulant interstitial fluid glucose levels in real time.

Inclusion Criteria:

• NUHS Postgraduate year 1 doctors
• Above 21 years of age
• Completing their year 1 rotations in 2021 or 2022

Exclusion Criteria:

• As this is an observational study with minimal risk, in an restricted pool of participants, no further exclusion criteria will be applied for participation.

NUHS Postgraduate year 1 doctors