Even with all the information about the importance of healthy sleep habits, many people still struggle to get a good night’s rest. In a world that is constantly “on,” it is hard to break away from the cycle of answering emails at night, checking the news, or just staring endlessly into the blue light of a cell phone or computer screen. This has led many people to have a varied bedtime, and ultimately what propelled researchers to analyze the effect it had on health.
It was found that individuals going to bed even 30 minutes later than their usual bedtime presented a significantly higher resting heart rate that lasted into the following day. This was linked to an increased risk of numerous health conditions including diabetes, stroke, and cardiovascular disease.
“We already know an increase in resting heart rate means an increased risk to cardiovascular health,” said Nitesh Chawla, lead author of the study. “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.”
A Four-Year Fitbit Study
For the study, Chawla and his team collected data from 557 college students who wore a Fitbit over the course of four years. A total of 255,736 sleep sessions were recorded which included measuring bedtimes, sleep, and resting heart rate.
In participants who went to bed anywhere between one and 30 minutes later than their normal bedtime, a significant increase in RHR was observed. Normal bedtime was defined as the one-hour interval surrounding a person’s median bedtime. The later they went to bed, the higher the increase in RHR.
“For some, it may be a matter of maintaining their regular ‘work week’ bedtime through the weekend,” said Chawla. “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 concluded that going to bed 30 minutes later or earlier than the median bedtime can lead to an increase in RHR. In some cases, RHR did level out during the sleep session, but in the majority, it lasted well into the following day. “Circadian rhythms, medications and lifestyle factors all come into play when it comes to healthy sleep habits,” Chawla said, “but it’s vital to consider consistency as well.”