 This study aimed to validate the Fitbit Charge II against portable home polysonography, PSG, in a shift work population of police officers and paramedics. The results showed that while the Fitbit provided reasonably accurate mean values for sleep and heart rate estimates, there were generally wide limits of agreement that hindered precision in quantifying individual sleep episodes. The study suggests that open-source algorithms, raw data access, and blinding participants to their own sleep data could enhance the value of this consumer-grade multi-sensor wearable in tackling clinical and research questions. This article was authored by Benjamin Stuckey, Ian Clark, Yasmin Azza, and others.