Social jet lag: Can a consistent sleep schedule protect your heart?

There are a few tried and true pieces of advice that sleep doctors always give for battling insomnia:

• Watch those alcoholic drinks at dinner,
• Cut the afternoon coffee,
• Stop scrolling before bed.
• And please, they beg – keep your sleep schedule consistent.

Flip-flopping between wake-up times – jolting awake at 7:30 on a Friday morning and then dozing until the afternoon on Saturday – wreaks havoc on our internal body clocks. Sleep experts refer to this as “social jet lag”, says Dr Sabra Abbott, a sleep medicine specialist. Similar to changing time zones, heading to bed at vastly different times from night to night may throw off your circadian rhythm.

And still, as anyone who’s worked a night shift, taken care of a toddler or fumbled back home after a party might tell you, going to bed and waking up at the same time is easier said than done. “It’s a luxury, right?” says Kelsie Full, a behavioural epidemiologist.

Full is the lead author of a new study that tied irregular sleep to an early marker of cardiovascular disease. Researchers examined a week’s worth of sleep data from 2,000 adults older than 45 and found that those who slept varying amounts each night and went to bed at different times were more likely to have hardened arteries than those with more regular sleep patterns.

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People whose overall sleep amounts varied by two or more hours from night to night throughout the week – getting five hours of sleep on Tuesday, say, and then eight hours on Wednesday – were particularly likely to have high levels of calcified fatty plaque built up in their arteries, compared with those who slept the same number of hours each night.

The study could not confirm that inconsistent sleep patterns definitively caused the heart issues, Full says. And the findings don’t necessarily mean that the occasional late night or very early morning should be off the table. “An off day or two is okay,” says Dr Tianyi Huang, an assistant professor of medicine at Harvard Medical School and a co-author of the study. “It’s more about the long-term pattern.”

For most people, if you have a night or two of inconsistent sleep timing, you’re likely not going to throw off your entire circadian rhythm, says Aric Prather, a psychologist and sleep specialist. And if you go to bed at 4am on a Saturday, you’re probably better off sleeping until noon and avoiding some of the acute effects of sleep loss than forcing yourself awake at the time you get up for work, he explains.

But the new study supports what previous research has theorised: Consistent sleep is crucial for health. A 2020 study found that people ages 45 to 84 with erratic sleep schedules were nearly twice as likely to develop cardiovascular disease compared with those with more regular sleep patterns. An analysis of more than 90,000 people linked circadian rhythm disruptions with a greater risk of mood disorders. Researchers have even tied irregular sleeping patterns to high cholesterol and high blood pressure.

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Over the last decade, researchers have strengthened the link between sleep and heart health, specifically. One theory for why consistent sleep helps your heart is that maintaining your circadian rhythm – the 24-hour cycle of your body’s internal clock – helps regulate cardiovascular function, Dr Huang says. And a mounting body of research shows that catching up on your sleep during the weekends can’t compensate for staying up during the week, he adds.

People often think that sleeping in after several nights of limited sleep or insomnia will make them feel better, says Dr Marri Horvat, a sleep specialist, “but it usually doesn’t help”.

“Keeping a regular, set schedule is more likely to put your body in a place where it needs to be to get a full night’s sleep going forward.”

So how do you actually get yourself to bed and wake up on a schedule? We asked sleep doctors to share their tips.

How to build a consistent sleep schedule:

Treat yourself

Set a wake-up goal that feels attainable (even if it’s challenging), Prather says, and then reward yourself for getting out of bed. That could mean heading to your favourite coffee shop or saving the show you’ve been looking forward to for Saturday morning instead of Friday night.

Focus on your pre-bedtime ritual

A regular bedtime routine – reading a few pages of a novel after you brush your teeth, for example – can help lock in a set sleep schedule. But the hours before you wind down for bed matter, too, Dr Horvat says. In the four hours or so before you head to bed, avoid alcohol, she suggests, and don’t work out (you may want to switch your dedicated exercise time to the morning). These shifts will help you fall asleep faster and stay asleep longer.

Find an accountability partner

Recruit a friend or a family member to get up around the same time you do, Prather recommends, and hold yourselves accountable by texting each other when you wake up. Even better: make an early(ish) plan for brunch or a morning walk to give yourself added motivation for getting up.

Get some sun

Light helps regulate our circadian rhythm, Dr Abbott says, signalling to our bodies that it’s time to wake up. Take a walk first thing, if the weather allows, to expose yourself to sunlight around the same time each day, she recommends.

Make your alarm as annoying as possible

If you can’t pry yourself out of bed on the weekends, Prather says, go for the nuclear option: opt for an alarm you can’t ignore. Set a grating song as your alarm tone, or try a puzzle alarm – an app that makes you solve a puzzle to shut it off. For extra incentive to wake up, keep your phone across the room at night, instead of by your bed, so you have to force yourself out of your covers to turn off the alarm.

Give yourself grace

“How aligned you are with your biological clock and how consistent you keep things does matter,” Prather says. “But that doesn’t mean every little moment, every week, matters.” Long-term sleep patterns are more important for overall health, he adds, rather than worrying about one or two nights’ bad sleep. “It takes the pressure off.” – This article originally appeared in the New York Times