In 2010, the American Heart Association (AHA) published its snazzy ‘Life’s Simple 7’ advice – seven measures used to assess heart health and predict disease.

These were dietary quality, physical activity, exposure to cigarette smoking, body mass index (BMI), fasting blood glucose, total cholesterol and blood pressure.

All of these were modifiable factors that determined if you were likely to have a heart attack or develop crippling cardiovascular disease – or if you were well protected.

They became the AHA’s guide by which doctors were meant to assess their patients.

How sleep affects your heart is a big conversation. Photo: Getty

Depending on how a patient scored on these metrics, their heart health and prospects were ranked ‘poor’, ‘intermediate’ or ‘ideal’.

Last year, the AHA added another metric and re-branded its diagnostic guide as ‘Life’s Essential 8’.

The new modifiable factor? Sleep: duration and quality.

The Australian Heart Foundation has told The New Daily that it’s looking to do something similar.

There’s been a push for this change

For years researchers have been finding strong associations between poor sleep (short, long and broken) and heart disease.

News media have repeatedly picked up on this theme, spurred by an interested public.

Just last week, US researchers found that sleep irregularity, particularly sleep duration irregularity, was associated with several measures of subclinical (read: ‘lurking’) atherosclerosis.

“Sleep regularity may be a modifiable target for reducing atherosclerosis risk,” the authors wrote.

Yes, it might be

Since 2019, I’ve personally published (with The New Daily) about a dozen pieces on the ways poor sleep appears to play havoc with your heart.

For a sample, see here, here, here and here. What’s emerged is an interesting question: should sleep be factored in more explicitly when drafting public health policy?

The Indian Heart Journal, in 2014, asked: ‘Sleep quality and duration – Potentially modifiable risk factors for Coronary Artery Disease?’

In 2021, the European Heart Journal published an article asked the same question about insomnia.  

In October, Columbia University Mailman School of Public Health published a study of 2000 older Americans.

Essentially, they added sleep to the AHA’s Life Simple 7 group of metrics to see how it would affect assessments.

They found that an assessment of cardiovascular health (CVH) that included sleep health “was more effective in predicting the risk of cardiovascular disease”.

The questions your doctor should be asking

Dr Nour Makarem is assistant professor of epidemiology at Columbia Mailman School of Public Health. She’s also the corresponding author of the new study. She said:

Associate Professor Nour Makarem.

“Healthcare providers should assess their patients’ sleep patterns, discuss sleep-related problems, and educate patients about the importance of prioritizing sleep to promote CVH (cardiovascular health).”

She said the formal integration of sleep health into CVH promotion guidance “will provide benchmarks for surveillance and ensure that sleep becomes an equal counterpart in public health policy to the attention and resources given to other lifestyle behaviours”.

By the time Dr Makarem’s paper was published, the AHA, had in fact included sleep in its Essential 8, which serves as a valuable public health tool for the general public and clinicians.

The new message is clear, from the American experts, anyway: when talking to your doctor about your heart health, along with those blood tests, the taking of blood pressure and discussing your lifestyle, include sleep in the conversation.

How many hours are you sleeping a night? Too many? Too few? What are you doing with the time when you can’t sleep? Are you tired all the time.

All good and valuable questions.

The Australian Heart Foundation agrees

Professor Garry Jennings is Chief Medical Advisor for the Australian Heart Foundation. He told TND that the foundation was “certainly thinking of picking up on the AHA approach and Australian-izing it”.

Professor Garry Jennings. the Australian Heart Foundation.

It’s early days, and “what’s in and out” in an Australian Essential Eight is yet to be teased out. But healthy sleep is an contender.

Professor Jennings said: “What we don’t have, apart from general advice about living a good life, is something specific about sleep.”

However, he said the idea of talking about sleep as a modifiable risk factor, an idea the Americans have adopted, is problematic.

He said: “There’s lot of evidence that people who sleep poorly have a higher risk of heart disease. People with sleep apnea in particular have a higher risk. But it’s not clear it’s a reversible risk.”

In other words, sleep isn’t like diet and exercise: if you improve the quality and quantity of what you’re eating, and get off the couch and start moving, there are clinically measurable benefits.

Whether getting people to sleep better “improves their outcomes”, we don’t know.

But the data on sleep in confused

Professor Jennings said: “The the data on sleep is very confused by the question of what makes people sleep poorly.” Is it alcohol abuse or sedatives or life stresses or obesity-related apnea?

“All these things may be in the background, contributing to that risk.
contributing to that risk… But what we’re not moving toward yet, because the data doesn’t support it, is naming sleep as an independent risk factor.”

In other words, it’s not there yet as a diagnostic measure.

But he added: “It doesn’t mean that it’s not a very good marker (indicator) of risk and our advice would be to people in the community and clinicians that they should ask about sleep habits.

“And for people who aren’t getting a healthy amount of quality sleep, to look at the reasons behind that.”

Why it’s complex and not fully understood

We know that smoking causes high blood pressure and increased heart rate which leads directly to strokes and heart attacks.

We know that eating too much causes high blood sugar which can damage blood vessels and the nerves that control your heart.

But how sleep affects the heart isn’t so straightforward. And neitgher are sleep experiments.

Here’s an example:

Last year I reported on studies from the Northwestern University Feinberg School of Medicine that looked at the impact of a light at night on participants’ sleep and heart health.

Keeping the TV on at night, disrupting sleep, has long been associated with obesity.

In one study, the participants were healthy young adults. When sleeping with “moderate overhead light” – about the equivalent of a day under heavy black clouds, or a TV set – experienced an increased heart rate while sleeping and impaired glucose metabolism the following morning.

In other words, increased risk factors for developing heart disease and diabetes were a consequence of sleeping for one night with dampened light.

Study with older people

In a second real-world study, 550 participants, aged 63 to 84, were exposed to light.

Less than half “consistently had a five-hour period of complete darkness per day”.

The rest of participants “were exposed to some light even during their darkest five-hour periods of the day, which were usually in the middle of their sleep at night”.

This went on for seven days and nights. Each participant wore an actigraph, a device worn like a wrist-watch that measured sleep cycles, average movement and light exposure.

Those who were exposed to any amount of light while sleeping at night “were significantly more likely to be obese”. They were also more likely to have high blood pressure and diabetes.

But this was a cross-sectional study. This means the investigators don’t know “if obesity, diabetes and hypertension cause people to sleep with a light on”. Or if the light contributed to the development of these conditions.

Plus, there was the confounding factor that exposure to light disrupts and weakens circadian signals

The researcher noted: There may be a biological explanation beyond disrupted sleep that ties light to an increased risk for obesity, diabetes and high blood pressure.

“It’s not natural to see those lights at night,” she said.

So yeah, it’s complex.