Sleep loss is increasingly being implicated in other health conditions as well. A Penn State study showed that short sleep combined with insomnia heightened the risk of hypertension. European data linked restless or otherwise troubled sleep in older adults to a 36 percent increased risk of Alzheimer's. More unexpected, researchers at the University of Wisconsin at Madison uncovered a link between sleep apnea and cancer mortality: Cancer deaths among patients with severe apnea were five times higher than among those without.