New US research has found that going to bed even just 30 minutes later than your usual bedtime could potentially increase your risk of cardiovascular disease.
Carried out by researchers at the University of Notre Dame in Indiana, the new study looked at data gathered from Fitbits worn by 557 college students over a four-year period.
In total, the Fitbits recorded 255,736 sleep sessions, and provided the researchers with information on the participants’ bedtimes, sleep and resting heart rate (RHR).
After analysing the data, the team found that when individuals went to bed anywhere between one and 30 minutes later than their normal bedtime, which was defined as the one-hour interval around a participant’s median bedtime, they experienced a significant increase in RHR which lasted into the following day.
The findings also showed that the later the participants went to bed, the higher the increase in RHR.
Surprisingly, participants who went to bed earlier than their usual bedtime also showed signs of increased RHR, although it depended on how much earlier — going to bed 30 minutes earlier than usual had little effect, but going to bed more than 30 minutes earlier significantly increased RHR.
“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.”
Although it is now well known that quality sleep is essential for good health, the researchers point out that usually guidelines only focus on the amount of sleep that we should get, which is often recommended to be around seven to eight hours each night. However, Chawla that there is more to consider as part of healthy sleep hygiene, and a consistent bedtime could also play a key role.
“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.”