Conclusions
CVD, DISEASES
The current study indicates that the effects of objective and self‐reported sleep duration on mortality are different in middle‐aged and older people. Objective sleep duration tended to have an inverse association with all‐cause and CVD mortality. A J‐shaped association was observed between self‐reported sleep duration and mortality. A short sleep duration in both objectively measured and self‐reported data was associated with increased all‐cause and CVD mortality. Insufficient sleep is an important public health concern. Self‐reported long sleep duration is also a concern, especially if it is caused by sleep fragmentation and underlying diseases. Importantly, self‐reported sleep duration is the most practical and cost‐effective research method, but it may not fully reflect real sleep duration. Long‐term monitoring of objective sleep duration can reflect the true level and fluctuation of sleep duration, and the development and popularization of smart wearable devices may provide a convenient means of collecting these data for studies in the near future.