Researchers in Europe say people who have trouble drifting off to sleep may be at increased risk of heart failure.
A study, published in the European Heart Journal, followed more than 50,000 people for 11 years.
Scientists found those who suffered several nights of poor sleep were more likely to develop the condition, in which the heart fails to pump properly.
Experts say further research is needed to see if a lack of sleep causes heart failure or the link is more complex.
Scientists at the Norwegian University of Science and Technology looked at more than 50,000 people aged between 20 and 89. At the beginning of the study, none of them were known to have heart failure.
People with the disorder may feel increasingly breathless and exhausted. And as heart failure worsens, it can be difficult to get a full night's rest.
During the research, participants were asked whether they had any difficulties getting to sleep or staying asleep and whether they felt fully restored after a night's slumber.
The BBC reports people who had trouble falling asleep and remaining asleep each night were three times more likely to develop heart failure than those who reported no trouble sleeping.
Those who experienced substandard sleep that failed to leave them fully refreshed were also at risk.
