According to a study published in the journal Neurology, people who have difficulty breathing while asleep (sleep apnea) are more likely to develop memory problems early on.
US scientists checked medical databases involving 2,400 people aged over 55.
Those who said they suffered from sleep apnea reported problems with their memory and thinking skills a decade earlier than people who slept well.
Further work is under way to clarify the link. It adds to growing evidence poor sleep is associated with illness.
In this condition the muscles around the throat relax and can block the airways, making it hard to breathe.
Patients often snore loudly and wake up several times a night.
Researchers are concerned in some cases this could mean vital organs – including the brain – are at risk of not getting the oxygen they require.
Scientists found people with the condition were more likely to report memory and thinking problems in their late 70s, on average 10 years before those who breathed easily while asleep.
The small number of patients who received treatment – using a continuous positive airway pressure (CPAP) machine that keeps the airways open and forces air in – did not report memory problems early on.
Researchers are now conducting larger studies to see whether CPAP therapy could help preserve memory and thinking power.