Five Things Every Middle Aged Adult Should Know About Sleep & Heart Disease.
Shortened sleep is the risk factor for heart disease most people miss, and it's a problem.
Most people do not know that sleep is a key factor when it comes to good cardiovascular health.
Because of this, sleep is pushed to the bottom of the list of priorities for addressing cardiovascular health.
In my view, this is a terrible idea.
Here is why.
Get Sleep Right. Get Everything Else Right.
There is a multitude of factors that will determine your cardiovascular risk.
Most of these factors are the consequence of good lifestyle choices.
Regular physical activity.
Good nutrition.
Not smoking.
Good mindset and cognitive well-being.
These are all key factors in what I refer to as the prevention pyramid. At the bottom are the four pillars of a good lifestyle: exercise, nutrition, sleep and stress.
In my view, sleep sits at the bottom of this pyramid.
If sleep goes wrong, the probability of getting the others going right is very low.
When you have gotten all four crucial lifestyle factors wrong, you are only left with medications and procedures.
This is the unfortunate reality for many people.
Here are five things everyone should know about sleep and heart disease.
Remember, if you get sleep right, you seriously increase your odds of getting the other factors right.
Poor Sleep Might Eliminate The Benefits Of Exercise & Dementia.
High levels of aerobic fitness are closely linked to lower rates of future dementia1.
Regular physical activity is arguably one of the biggest factors preventing dementia.
But what if all that effort was going to waste because of poor sleep?
The problem is, it might be.
As we get older, the risk of dementia increases for everyone, regardless of risk factor control. The goal is to delay the decline in cognitive function for as long as possible.
A recent study looked at people over 50 and tracked them over ten years to assess their rate of cognitive decline2.
They found that higher levels of physical activity delayed the rate of decline in cognitive function, except in those with shortened sleep, i.e. those who frequently had less than 6 hours of sleep per night.
So if your goal is to delay dementia with high levels of physical activity and you are consistently not getting enough sleep, then your efforts may well all be for nought.
Remember, prevention is rarely about getting just one thing right.
It is about getting multiple things right.
When it comes to preventing dementia, this could not be truer.
Poor Sleep Is A Major Risk Factor For Insulin Resistance.
Insulin resistance is a significant driver of cardiovascular risk.
Insulin resistance is a precursor condition to metabolic syndrome and type 2 diabetes, both major drivers of heart disease.
One of the issues with insulin resistance is that it is silent and is rarely formally tested.
This means that changes at this level frequently go unnoticed.
When insulin resistance markers were assessed in those who were getting their regular night sleep versus those who were getting a 40% reduction in regular sleep, the impact was very clear3.
Shortened sleep was linked to a 20% worsening of insulin resistance measures.
And this was only over a four-day period.
Just think of what years of shortened sleep translates into.
Insulin resistance is a major driver of risk, and shortened sleep is a quick way to get there.
Short Sleep Is Causing You To Eat More Calories.
Obesity is one of the biggest global health concerns we face today.
Obesity is also a key driver of risk for cardiovascular disease.
Although there are many factors linked to obesity, one factor is certain: excess caloric intake leads to an excess in the energy balance.
The problem is that shortened sleep may be a substantial driver of excess caloric intake.
Everyone knows that after a poor night's sleep, we tend to make poor food choices the following day, often favouring foods high in energy density.
When you compare sleeping 6.5 hours per night versus 8.5 hours per night, there is a substantial difference in calorie intake between the two groups4.
Over the two-week study period, those sleeping 8.5 hours per night consumed 270 calories less per day than those in the 6.5-hour sleep-per-night group.
For every hour of added sleep, a person's daily calorie intake is reduced by 160 calories.
Minimising the potential for excess energy intake is critical to preventing obesity and its cardiovascular risks.
Avoiding shortened sleep is likely an important ingredient in hitting that goal.
Poor Sleep Increases The Rate Of Heart Attacks & Stroke.
Shortened sleep is now recognised as part of the eight key factors of good cardiovascular health.
Not only is short sleep linked to the development of more risk factors for heart disease, such as high blood pressure, but it is also linked to a 20% increase in the rates of heart attack5.
Shortened sleep, this time less than 5 hours per night, is also associated with a greater than 3-fold increase in the risk of stroke compared to those getting 7 hours of sleep per night6.
While all of the studies that assess outcomes over longer periods of time rely on observational data, and the risk of issues with confounders exists, there is a growing body of evidence that good sleep is linked to better cardiovascular health.
Alcohol & Caffeine Impair Sleep Quality & Duration.
It is rare to encounter someone who does not consume either caffeine or alcohol.
Both have the potential to impair the quality and duration of sleep.
Like any compound, they have a half-life, which means that the closer to sleep they are consumed, the greater the potential for impacting sleep.
Alcohol is less likely to influence the duration of time you sleep but is very likely to impair the quality of sleep you get.
Alcohol consumption does make you fall asleep faster but significantly decreases the time you spend in REM sleep and increases the amount of time you spend in stage 1 or light sleep7.
This is why you can consume alcohol, get to sleep quite quickly and may sleep for your usual time in bed but not feel rested the next day.
You have spent the same time unconscious, but the amount of time you spent getting deep restorative sleep has been reduced.
Caffeine consumption is more of an issue for sleep duration.
Drinking caffeine in any form later in the day increases the time it takes to get to sleep by 20 minutes and decreases total sleep time by 45 minutes8.
However, like so many things in life, the dose makes the poison.
For both alcohol and caffeine, smaller amounts consumed earlier in the day are less likely to impact sleep duration and quality.
Personally, I consume both caffeine and alcohol. Very little alcohol but lots of caffeine.
I do not drink caffeine after 1 pm and have grown far more partial to a mid-day gin and tonic on the weekends.
But do whatever works for you.
Good Sleep Is An Underrecognised Factor For Good Cardiovascular Health.
As I write this article, I can hear my seven-month-old baby crying in the next room as my wife is currently sleep-training him.
Last night was no fun, and my sleep was worse than usual, both in duration and quality.
I think my wife would use more colourful language to describe her sleep last night.
But this is a phase that will pass.
The question is, outside of short periods of unavoidable sleep interruption, will you prioritise good sleep to optimise your cardiovascular health?
Because when things start to slip, as they often do, I want you to remember five important points that connect sleep and cardiovascular health.
Poor Sleep Might Eliminate The Benefits Of Exercise & Dementia.
Poor Sleep Is A Major Risk Factor For Insulin Resistance.
Short Sleep Is Causing You To Eat More Calories.
Poor Sleep Increases The Rate Of Heart Attacks & Stroke.
Alcohol & Caffeine Impair Sleep Quality & Duration.
When You Are Ready, Here Is How We Can Help.
For an accessible and comprehensive overview of understanding and managing heart health, you can check out the best-selling book Heart. An Owner’s Guide.
For those based in Ireland, Dr Barrett works with a small number of clients to provide a comprehensive evaluation of cardiovascular risk and a tactical approach to maximally reducing that risk.
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In Case You Missed Them:
Midlife cardiovascular fitness and dementia: A 44-year longitudinal population study in women. Neurology. 2018 Apr 10;90(15):e1298-e1305.
Joint associations of physical activity and sleep duration with cognitive ageing: longitudinal analysis of an English cohort study. Lancet Healthy Longev. 2023 Jul;4(7):e345-e353.
Effect of sleep restriction on insulin sensitivity and energy metabolism in postmenopausal women: A randomized crossover trial. Obesity (Silver Spring). 2023 May;31(5):1204-1215.
Effect of Sleep Extension on Objectively Assessed Energy Intake Among Adults With Overweight in Real-life Settings: A Randomized Clinical Trial. JAMA Intern Med. Published online February 07, 2022.
Sleep Duration and Myocardial Infarction. J Am Coll Cardiol. 2019 Sep 10;74(10):1304-1314.
Sleep Patterns and the Risk of Acute Stroke: Results From the INTERSTROKE International Case-Control Study. Neurology. 2023 May 23;100(21):e2191-e2203.
Alcohol and the sleeping brain. Handb Clin Neurol. 2014;125:415-31.
The effect of caffeine on subsequent sleep: A systematic review and meta-analysis. Sleep Med Rev. 2023 Feb 6;69:101764.
Very important and my biggest remaining risk factor. Despite being in bed ~8 hours almost every night, my Apple Watch indicates 6.5-7 hours of sleep at the most. No alcohol at all and no caffeine after 9 am. A hard problem to solve.
I am concerned about Dr. Barrett's header: "Poor Sleep Might Eliminate The Benefits Of Exercise & Dementia." That suggests there are benefits to dementia. If so, what are they? Thank you.
James G. Tappan, M.D.