Elderly people who spend little time in deep sleep may be at higher risk of developing high blood pressure (hypertension), a U.S. study suggests.
When sleeping, healthy individuals spend about 20% to 25% of their sleeping time in a deep sleep – known as slow-wave sleep. This sleep phase is considered restorative and has been shown to be important for memory and mental performance.
In a study, which included 784 men over the age of 65, researchers measured their sleep pattern over one night and looked at their risk of having high blood pressure up to three years later.
High blood pressure was defined as having blood pressure greater than 140/90 mmHg or reported use of blood pressure lowering medication.
The patients were split into groups based on the percentage of time asleep spent in slow-wave sleep. The researchers found that those in the group who spent less than 4% of their sleep time in the slow-wave phase had a 1.83-fold increased risk of hypertension compared with those who spent 17% of the night in deep sleep.
“Our study shows for the first time that poor quality sleep, reflected by reduced slow wave sleep, puts individuals at significantly increased risk of high blood pressure,” said Dr. Susan Redline, one of the study authors and a professor of sleep medicine at Harvard Medical School.
“Although women were not included in this study, it’s quite likely that those who have lower levels of slow wave sleep for any number of reasons may also have an increased risk of developing high blood pressure,” she added.
The report said further studies were needed to determine if improving sleep could reduce the risk.
Natasha Stewart, senior cardiac nurse at the British Heart Foundation, said: “Even though this study does suggest a link between poor sleep and the development of high blood pressure, it only looked at men aged over 65.
“We still need more research in other age groups and involving women to confirm this particular association. However, we do know more generally that sleep is essential for staying healthy. It’s important we all try to make sleep a priority and get our 6 to 8 hours of shut-eye a night.”
Dr. Susan Redline said that going to bed and waking up at the same time each day, avoiding alcohol and caffeine before bedtime, and other good sleep hygiene practices can help people sleep longer and more deeply.
But the most important thing to maximize slow-wave sleep is to ensure that there is not a sleep disorder, like sleep apnea or periodic leg movement, that is causing disruptions.