Primary outcome
The study’s primary outcome was sleep quality defined by sleep efficiency, as measured by the Fitbit™ Charge 2 wrist device. This is a consumer wristband-tracking device that embeds a heart rate monitor and three-axis accelerometer to report heart rate, exercise and sleep. Raw data from the device was uploaded to Fitbit, which processed it using a proprietary algorithm. Data reported back from Fitbit included subject ID, date of sleep, start time, end time, minutes asleep, minutes in sleep period and sleep efficiency. Other parameters, were also reported, including sleep stages, but this data was not deemed reliable enough to use in the analysis. All statistics on sleep data were performed by our Study Statistician as noted below.The FitBit™ Charge 2 was introduced in 2016 and replaced in 2019 by improved devices. Cost, ease of use by persons in a natural sleep environment, the amount of data collected, the inessential requirement for specialized technicians to interpret the date are some of the advantages of consumer actigraphy over the gold standard polysomnography (PSG) [Sleep efficiency is defined as the percentage of time asleep while in bed during a specified sleep period. A normal sleep efficiency is at least 85%. This was calculated from the longest recorded sleep period (> = two hours) during a 24 h period that occurred within or overlapped between 8:00 pm and 8:00 am. In order to distinguish a sleep period from a daytime nap, the onset, but not the end of the sleep period, had to fall within the sleep window [