A newly published study from researchers at Brigham and Women’s Hospital in Boston is suggesting irregular sleep patterns, such as inconsistent bedtimes from day to day, can potentially double a person’s risk of developing cardiovascular disease.
"When we talk about interventions to prevent heart attacks and stroke, we focus on diet and exercise," says Tianyi Huang, lead author on the new study. "Even when we talk about sleep, we tend to focus on duration – how many hours a person sleeps each night – but not on sleep irregularity and the impact of going to bed at different times or sleeping different amounts from night to night.”
A great deal of recent research has affirmed the importance of sleeping a solid eight hours every night. Too little sleep can increase your risk of diabetes, too much sleep has been linked to stroke, and optimal cognitive performance during the day can be tied to an ideal duration of sleep. But how much of an effect do irregular sleep patterns have on a person’s health? Are the benefits of a solid eight hours undercut if you go to sleep at different times every night?
A 2019 study from Brigham and Women’s Hospital raised this possibility after evaluating data from a long-term research project called the Multi-Ethnic Study of Atherosclerosis (MESA). Part of the study involved participants recording sleep patterns across a seven-day period using an activity tracking wearable device. The participants general health was then followed for an average of five years.
Last year’s study revealed those subjects with the greatest variation in bedtimes from night to night were more likely to develop metabolic disorders such as hypertension, obesity and diabetes. The new study is now presenting an association between irregular sleep patterns and cardiovascular events.
The most irregular sleep patterns determined in the new study were defined as bedtimes differing by 90 minutes or more each night, and sleep durations varying by two hours or more each night. Those subjects with these these most irregular sleep patterns displayed nearly double the amount of cardiovascular events across the five year follow-up period, compared to those subjects with the most consistent sleep patterns.
“Our study indicates that healthy sleep isn't just about quantity but also about variability, and that this can have an important effect on heart health,” says Huang.
While the research is undeniably compelling and novel, it does suffer from the same limitations as last year’s study. Data gathered from self-reported sleep diaries and questionaries is notoriously inconsistent, and the participants’ sleep patterns were only objectively tracked for a seven-day stretch at the beginning of the study. So, it is unclear how consistent these irregular sleep patterns were across the entire five-year study.
The study is also not designed to offer insight into causal connections between irregular sleep patterns and cardiovascular health. It could be that variable bedtimes and inconsistent sleep durations are symptoms of other harmful lifestyle behaviors that are causing the negative health consequences.
The researchers do hypothesize consistent circadian rhythm disruptions as the potential causal mechanism resulting in the increased risk of cardiovascular events. Other recent research has indeed found links between metabolic disease and circadian rhythm disruptions, so this hypothesis is not a stretch. However, further work is certainly needed to better understand the correlation uncovered in this new study.
"Sleep regularity is a modifiable behavior,” says Huang. “In the future, we'd like to explore whether changing one's sleep patterns by going to bed consistently each night may reduce a person's risk of future cardiovascular events.”
The new study was published in the Journal of the American College of Cardiology.
Source: NIH/Brigham and Women’s Hospital via Eurekalert
As a physician I think the comments panning this study - anecdotal as it may seem since even WE don't give 'self-reported study findings' great weight - are rather out of line. This is information from a self-reported study poorly designed and just chipping at the tip of an iceberg on heart disease causation that ties into what MANY, MANY OTHER WELL CONSTRUCTED STUDIES ON SLEEP HYGIENE HAVE FOUND!!!!
Sleep hygiene, like clean healthy teeth, is something requiring a proactive approach. Absolutely try to go to bed at a set time for at least 3 weeks straight and then allow only small variances until your body begins to tell you that your sleep cycle should be starting. In the U.S.A., we are going to the 'Daylight Saving's Time', quite a misnomer as it isn't daylight that it saves and it is an added burden on the body - but it has given researchers and statisticians a lot of data in the years past.
Now, like Oral Hygiene & Incidences of Heart Disease studies yielding new information on oral health and heart disease, we are finding that poor sleep hygiene - like poor oral hygiene - can ABSOLUTELY SET US UP FOR A HIGHER INCIDENCE OF CARDIOVASCULAR DISEASE! - The Lancet:Volume 366, Issue 9499, 19–25 November 2005, Pages 1809-1820 which gives only an abstract ~~~~British Medical Journal 1993; 306, website:https://www.bmj.com/content/306/6879/688.short which gives a downloadable pdf
What to do with Rich Hardy's article here on New Atlas? Cry about insomnia? Discuss the specifics of the findings as to what is legitimate evidence based data and what is conjecture? Why don't readers do exactly all of those instead of thinking about the prescient findings?
This study is based on self reporting but in medicine we have multiple studies connecting a similar syndrome (@AlexD alluded to it), Sleep Apnea. Intermittent sleeping due to a neurological - and yes, sleep apnea is NOT JUST MECHANICAL, but can be a theorized brain stem issue since the signals to breathe are not sent through certain parts of the sleep cycle - and the mechanical apnea syndromes of excessive abdominal girth & mass, poor muscle tone of the neck (you don't see nearly as much severe snoring or sleep apnea in brass and woodwind patients) and other oropharynx issues. Those studies - although corollary and not precisely causal - have shown in almost all populations an increase in obesity, diabetes, hypertension, I believe even kidney disorders as well as higher stress related compounds in the blood with poor sleep in identified apnea patients. Which means concomitant increased heart disease risk and stroke risk increases are seen, as well as sometimes difficulties in marriages and significant other living arrangements as many CPAP and BiPAP machines aren't conducive to 'comfortable and restful' co-sleeping.
The mechanism of associated disease induction is not clear and agreed upon, but the increased risk of untreated and poorly treated sleep apnea remain evident and relevant.
These findings are likely reproducible and one day will be verified with larger longitudinal studies - we just haven't been crunching the data for thousands of people over their lifetimes regarding sleep hygiene as we have diet in say the Framingham study.
Please think about what you are doing to your bodies by living with frustrating but modifiable routines of eating or sleeping. We have several well received approaches to beating the "jet-lag" our modern pace requires, but other than adapting those approaches (start going to bed earlier the week before the time change) with the U.S.A.'s DST change will still result in a higher incidence of automobile incidences the first week, an uptick in panic attacks and mild heart problems, and indigestion issues across America.
You CAN train yourself to fall asleep but you have to start eliminating the barriers. 1st - keep a set bedtime, do not vary, for at least 3 weeks.
2nd - make the sleeping chambers as conducive to JUST SLEEP as possible, no reading, no watching TV, no surfing the web, no texting or phone calls, and so forth....activities other than sleep too numerous to mention....
3rd - try to pin point sources of stress in your life that you can't shake when you are trying to go to sleep. A relationship falling apart is NOT conducive to developing a great sleep routine although the subsequent depression may keep you in bed for hours. So deal with the arthritis or noisy neighborhood dog (peacefully and resolutely if possible) or heartburn every time you are supine (see a medical specialist) and if it is an emotional issue like a child that is not behaving properly, seek counseling.
4th - if all the blocks to sleep seem gone but sleep doesn't result, there are supplements that help and there are medications that help.
And lastly - brush your teeth regularly for 2 minutes or more, just like washing your hands during the virus season while you sing the "Happy Birthday" song through twice. These steps can only improve your health and quality of life, but it is good to see New Atlas readers ready for joining a discussion.