It should be made clear that not everyone has a device to record their sleep patterns; in some of these nations, it's likely that only the richest people do.
Not all experience and knowledge related to problem-solving can be obtained by personal effort alone due to limitations of mind and capabilities of each individual.
It is a luxury in such circumstances to expect individual attention, especially in classes where students in the back rows can hardly see the blackboard.
But compared with that group, the risk of dying from all causes was twice as great among the sun avoiders and 40% higher in those with moderate sun exposure.