Difficulty falling asleep at night may be due to high blood pressure. A new study from China reveals that insomnia can lead to hypertension later in life. In particular, insomniacs who experience greater than ordinary alertness throughout the day, or ‘hyperarousal’ as it is termed, have the highest risk. Hyperarousal is linked with the increased secretion of cortisol, a steroid hormone that your body generally only releases in times of stress.

300 adults participated in the study, including 200 chronic insomniacs who have had trouble sleeping for over six months. Each participant spent one night in the Sleep Medicine Center of the West China Hospital. There, they were able to sleep as they normally would in light, sound, and temperature controlled rooms.

The next day, they were given sleepiness/ alertness tests. During the day, they had four opportunities to take a 20-minute nap. The researchers took note of their sleep latency. In other words, they measured how long it took each participant to fall asleep during the day. The researchers also took the participants’ blood pressure periodically throughout the study.

For the participants without any sleep disorders, falling asleep quickly or taking some time to fall asleep during the nap period had no correlation with their blood pressure.

However, for the chronic insomniacs, the longer it took them to fall asleep during the nap period, the more likely they were to have high blood pressure- even when adjusting for variables such as age, gender, weight, smoking habits, and use of caffeine.

People who took more than 14 minutes to fall asleep were three times as likely to have high blood pressure, some would even qualify for a doctor’s diagnosis of hypertension. Both insomniacs and normal sleepers who fell asleep in under 14 minutes had no signs of increased blood pressure.

“Insomniacs who have either short sleep at night or show signs of hyperalertness during the day are at risk for hypertension,” said coauthors Dr. Xiangdong Tang of Sichuan University in China and Dr. Alexandros N. Vgontzas of Penn State University College of Medicine.

This is the first study to link insomnia with hypertension. The study’s authors advise anyone who has trouble falling asleep at night to check their blood pressure. Screening for blood pressure is a simple and painless procedure that does not even need to be done at a doctor’s office. Major pharmacies such as Walgreens, CVS, and Osco have equipment onsite that allows you to check your blood pressure without the stress of going to the doctor’s.