We all know that going to bed at specific times on a regular basis isn’t good for your sleep health – but a new study suggests it could be deadly.

New research suggests that an irregular sleep schedule may increase the risk of serious cardiovascular events such as heart disease or stroke, even if you get the recommended seven to nine hours of sleep per night.

Previous studies have focused primarily on the health effects of sleep duration rather than the effects of a stable sleep-wake cycle, so these results are significant.

“Our results suggest that sleep regularity may be more relevant in modulating MACE (major cardiovascular event) risk than adequate sleep duration,” the study research team said.

For the study, 72,269 people aged 40 to 79 wore an activity tracker for a week to assess their sleep patterns. None of the participants had a history of heart disease or stroke.

Data were then collected to calculate each participant’s sleep regularity index score. People with a score above 87 were considered to have a regular sleep rhythm, while those with scores below 72 were considered to have an irregular sleep rhythm. Those in between were classified as “moderately regular.”

The research team then collected data on stroke, heart failure and heart attack cases over the next eight years and found that irregular sleepers had a 26% higher risk of suffering a major cardiovascular event than those who slept around the same time Went to bed at the same time that night.

Participants whose sleep schedule was moderately regular were 8% more likely to experience this type of life-threatening event.

The study also showed that those with a regular sleep schedule were more likely to get the recommended hours of sleep per night – which is seven to eight hours for those over 65 and seven to nine hours for those aged 18 to 64.

Additionally, they found that attempting to make up for lost sleep does not offset cardiovascular risks in irregular sleepers.

These results were published Tuesday in the Journal of Epidemiology & Community Health.

The study had certain limitations, including that sleep data was only collected over the course of a week and the sleep tracker did not distinguish between sleep and conscious rest. Naps were also not taken into account.

Still, this new research suggests that there is a strong link between failing to go to bed at the same time every night and the risk of heart disease or stroke.

“The results of this study suggest that sleep regularity needs to receive more attention in public health guidelines and clinical practice due to its potential role in cardiovascular health,” the study authors said.