A study in the April 1 issue of the journal SLEEP is the first to demonstrate that chronic insomnia with objectively measured short sleep time is an independent and clinically significant risk factor for hypertension.
Results indicate that participants with insomnia and an objectively measured, severely short sleep duration of less than five hours had a risk for hypertension that was 500 percent higher than participants without insomnia who slept more than six hours. People with insomnia and a moderately short sleep duration of five to six hours had a risk for hypertension that was 350 percent higher than normal sleepers.
In contrast, neither insomnia with a normal sleep duration of more than six hours nor a short sleep duration without a sleep complaint was associated with a significant risk for hypertension. This suggests that there is an additive or synergistic effect on hypertension risk when insomnia occurs in combination with a short sleep duration.
According to lead author Alexandros N. Vgontzas, MD, director of the Sleep Research and Treatment Center at the Penn State College of Medicine in Hershey, Pa., one of the study's strengths is that sleep duration was measured objectively by overnight polysomnography.
"It should be emphasized that many times the amount that we feel we slept is different from the actual amount," said Vgontzas. "Thus self-reported sleep duration cannot replace measured sleep duration."
The study involved a random sample of 1,741 men and women in central Pennsylvania with an average age of 49 years. Eight percent were classified as having chronic insomnia with symptoms persisting for at least one year; 22 percent were poor sleepers with a moderate to severe complaint of difficulty falling asleep, staying asleep, early final awakening or unrefreshing sleep; and 70 percent were normal sleepers. Twenty-one percent had a severely short sleep duration of less than five hours; 23 percent had a moderately short sleep duration of five to six hours; and 56 percent had a normal sleep duration of more than six hours.