"Our study suggests that achieving normal sleep may be protective for some people with these health conditions and risks," said lead study author Julio Fernandez-Mendoza from Penn State Health Milton S. Hershey Medical Center in Hershey in Pennsylvania, US.
"However, further research is needed to examine whether improving and increasing sleep through medical or behavioural therapies can reduce risk of early death," Fernandez-Mendoza said.
For the study, the researchers analysed the data of more than 1,600 adults who were categorised into two groups as having stage 2 high blood pressure or Type-2 diabetes and having heart disease or stroke.
Participants were studied in the sleep laboratory for one night and then researchers tracked their cause of death up to the end of 2016.
The researchers found that of the 512 people who passed away, one-third died of heart disease or stroke and one-fourth died due to cancer.
People who had high blood pressure or diabetes and slept less than six hours had twice the increased risk of dying from heart disease or stroke, showed the findings published in the Journal of the American Heart Association.
People who had heart disease or stroke and slept less than six hours had three times the increased risk of dying from cancer.
The increased risk of early death for people with high blood pressure or diabetes was negligible if they slept for more than six hours, the research showed.
"Short sleep duration should be included as a useful risk factor to predict the long-term outcomes of people with these health conditions and as a target of primary and specialised clinical practices," Fernandez-Mendoza said.
( With inputs from IANS )