It's not just the result of poor health causing more sleep. Both can be caused by a third factor. Chronic lack of exercise causes people to sleep 9+ hours per day. Put those same people on regular aerobic exercise regimes, and they start sleeping <8 hours.
Also, it's not the most outrageous hypothesis that oversleeping directly causes health problems, too. The body is complicated and poorly understood.
Also, it's not the most outrageous hypothesis that oversleeping directly causes health problems, too. The body is complicated and poorly understood.