April 27, 2026 | Categories: Health, Sleep
You stay up late to watch one more hour-long episode of a series, telling yourself you’ll make up for lost sleep on the weekend. Or, you find yourself catching up on Slack at night because have a few minutes of quiet. No big deal delaying bedtime by 90 minutes or so, right? Those bedtime shifts feel harmless. A new study from the University of Oulu suggests they’re not.
The study, published in BMC Cardiovascular Disorders looked at over 3,200 participants from a 1966 cohort who attended a follow up in 2012 and then followed them until 2023 to note who experienced a MACE (acute myocardial infarction, stroke, unstable angina, heart failure hospitalization, or cardiovascular disease-related death). They tracked sleep patterns and deviations over the course of seven days via a wearable device when the participants hit age 46. The researchers were looking to note deviations from the participants bedtime, wake-up, and sleep midpoint, and established eight hours as the “average sleep duration” to note trends above or below.
They discovered that when sleep duration fell below eight hours, it wasn’t just the hours people slept that mattered, it was the unpredictability of when they went to sleep. Variability in bedtime by about 90 minutes (versus 30 minutes for a standard night) and/or sleep midpoint variability each showed significant risk factors for MACEs. Individuals with irregular bedtimes had twice the higher risk of MACEs compared to those with regular bedtimes. Surprisingly, variability in wake-up time did not show the same association amongst those who didn’t sleep as many hours or those who snoozed for eight or so.
If you’re treating sleep like a “nice to have” instead of the crucial pillar that contributes to better overall health, these findings might be the wake up call you need to establish a bedtime routine.
Sleep consistency isn’t just something to try for, it’s how your body regulates itself. When your bedtime shifts erratically, you’re essentially asking your cardiovascular system to adapt to a fluctuating process night after night. Over time, that chronic variability adds up.
This isn’t the first time science has pointed to irregular bedtime schedules impacting cardiovascular health, but it is the first time researchers looked separately at bedtime variability, wake-up time and the midpoint of the sleep period while factoring in their independent associations with major cardiac events, lead postdoctoral researcher Laura Nauha from the University of Oulu, said in a press release.
“Our findings suggest that the regularity of bedtime may be important for heart health. It reflects the rhythms of everyday life—and how much they fluctuate,” Nauha said in the release.
Although phones sometimes interfere with sleep, they can help remind you to set a bedtime schedule when you turn on a Sleep Focus (on iOS) or Sleep Mode (on Android). Set the reminder to go off at least 30 minutes before you want to fall asleep so you can start the wind-down routine.
Many leaders have to catch an early flight for a conference or meet a client for breakfast, which means they need to set a morning alarm earlier. While this study find didn’t find that erratic wakeup times were associated with an increased risk of a cardiac issues, other studies say that high day-to-day variations in sleep duration have associations with cardiovascular disease. In general, waking up around the same time each day is considered an important part of sleep hygiene, sleep experts recommend.
When I talked to clinical sleep specialist Michael Breus, PhD, earlier this year for sleep industry trend predictions, he told me that waking up around the same time every day was extremely important for improving sleep quality. Rising at the same time seven days a week directly impacts how your body produces melatonin at night, Breus told me. “If all people did was this, it would it would give them 75% improvement in their sleep—just wake up at the same time every day.”
If you’re reading this and feeling concern about the “late nights” you anticipate before a launch or worry about your previous mistakes, don’t let these findings leave you tossing and turning all night. (Pun intended.)
The study isn’t saying that the occasional late night you spent at the office will directly impact your heart health right away or staying out later than your standard bedtime is setting you up for cardiovascular issues. It’s noting associations and patterns. Those who don’t stick to a regular bedtime schedule for the long haul or prioritize sleep as part of a wellness program could be putting additional stress on their hearts over time.
The takeaway? Don’t stress about every late night. Stop treating your sleep schedule as the most flexible thing on your calendar.
This article was originally written for Inc.com.
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