An inconsistent bedtime can cause your resting heart rate to spike

NOTRE DAME, Ind. — Many sleep studies show how critical a good night’s sleep is to our overall health. Most agree getting at least seven hours of rest each night can reduce the risk of numerous health conditions, such as stroke, cardiovascular disease, and diabetes. While the amount of sleep you get is important, one study adds when you go to bed is just as critical to your health. Researchers at University of Notre Dame find a constantly changing bedtime can have a negative impact on your heart rate.

The study examines the correlation between regular bedtimes and resting heart rate (RHR). The results find people who go to bed even 30 minutes later than their normal bedtime have a significantly higher RHR that continues into the following day.

“We already know an increase in resting heart rate means an increased risk to cardiovascular health,” says lead author Nitesh Chawla in a media release. “Through our study, we found that even if you get seven hours of sleep a night, if you’re not going to bed at the same time each night, not only does your resting heart rate increase while you sleep, it carries over into the next day.”

How bedtime is tied to resting heart rate

Chawla and his team analyzed data collected on 557 college students via Fitbit over four years. In total, the team looks 255,736 sleep sessions, measuring each person’s bedtimes, sleep patterns, and resting heart rate. The results show significant increases in RHR when individuals hit the pillow between one and 30 minutes later than their routine bedtime. For the study, the Notre Dame team considers anything within one hour of a participant’s average bedtime normal. The later someone goes to bed, the higher their RHR increase.

A surprising finding is that going to bed earlier than normal also increases a person’s resting heart rate, but it depends on how early they fall asleep. Going to bed 30 minutes earlier than normal has little impact, but going to bed more than a half-hour earlier greatly increases RHR. Luckily, researchers say this change levels out during the night.

From work responsibilities to cell phone addictions, it’s getting more difficult to find the time to sleep properly every day. While circadian rhythms, medications, and lifestyle factors all affect healthy sleep habits, Chawla warns that we must also consider sleep consistency, too.

“For some, it may be a matter of maintaining their regular ‘work week’ bedtime through the weekend,” the professor of Computer Science and Engineering adds. “For shift workers and those who travel frequently, getting to bed at the same time each night is a challenge. Establishing a healthy bedtime routine — as best you can — is obviously step number one. But sticking to it is just as important.”

The study was published in NPJ Digital Medicine.