A new study released by the American Heart Association suggests a strong correlation between insomnia and high blood pressure. The study is the first to define whether insomnia is linked to a longer time to fall asleep.
Insomnia is a fairly common condition and affects one-fourth to one third of the general population. Researchers studies 219 chronic insomniacs and 96 normal sleepers. Insomnia is defined as difficulty sleeping for more than 6 months. The research participants spent one night monitored in a asleep lab and were subjected to the Multiple Latency Sleep Test the next day. Half the participants took 14 minutes or less to fall asleep and half took more than 14 minutes to fall asleep. Those that took more than 14 minutes to fall asleep were considered “hyperaroused.”
“We observed a strong correlation between the degree of physiological hyperarousal and hypertension,” said Xiangdong Tang M.D., Ph.D, co- author of the study and professor of sleep medicine at West China Hospital, Sichuan University in Chengdu, China.
“In other words, those insomniacs who were hyperalert during the day and unable to relax and fall asleep during the Multiple Latency Sleep Test (MSLT) had the higher risk of hypertension,” said study co-author Alexandros Vgontzas, M.D., professor of sleep research and treatment in the Department of Psychiatry at Pennsylvania State University College of Medicine in Hershey, Penn.
The hypertension diagnosis was defined based on blood pressure measures or a physician’s diagnosis. Researchers controlled for confounding factors such as obesity, sleep apnea, diabetes, smoking, alcohol and caffeine use.
The findings revealed that chronic insomnia combined with an MSLT score greater than 14 minutes increased the risk of high blood pressure by 300 percent. MSLT scores greater than 17 minutes increased the risk by 400 percent.
“Long latency times to fall asleep during the day may be a reliable index of the physiological hyperarousal and biological severity of the disorder,” Vgontzas said.
“Although insomniacs complain of fatigue and tiredness during the day, their problem is that they cannot relax and that they are hyper,” he said. “Measures that apply in sleep-deprived normal sleepers — napping, caffeine use or other stimulants to combat fatigue — do not apply in insomniacs. In fact, excessive caffeine worsens the hyperarousal.”