Sleep 6.2 The Clinical Importance of Sleep Regularity

Key studies, including UK Biobank and a 2023 consensus review, show irregular sleep has stronger health consequences than sleep duration alone.

Video Breakdown:

00:00 Key Findings from the UK Biobank Study

02:36 Consensus Statement and Broader Implications

So that's a little bit of the intro to Sleep regularity, and let me talk a little bit about the clinical significance of sleep regularity.
Now this is a quick summary of that study done by Dan Windred and Andrew Phillips in the UK Biobank in 2024. So the UK Biobank is a large epidemiological study done in the UK. There's about 61,000 participants in this specific study who were asked to wear an actigraphy device for one week at baseline.
So this was done at the very beginning of this study, and so each individual wore it for about a week. There was an average,follow up about 7.8 years. And again, this study used the SRI or the Sleep Regularity Index developed by Andrew Phillips. And this is the plot showing the effect of sleep duration.
And you could see the years since the accelerometer recording on the X axis, the proportion of surviving on the Y axis. And what this study group did was to divide the sleep duration into quintiles, so five separate groups, and the one with the lowest amount of sleep is de marketed here in red.
You could see that the one in red clearly did the worst, but the first four quintiles, it was hard to, see the difference between them. So the demarcation in terms of the dosing was not as clear. Now they did the same thing, but they applied this now to sleep regularity and divided into the five quintiles again, but again categorized according to the SRI score.
And so the green is the one with the highest regularity. Purple is intermediate and red is very the lowest, and you could see much more of a significant dose response. You could see the demarcations between the highest four quintiles, but even the lowest quintile for the sleep regularity index has the highest mortality.
This led them to conclude that sleep irregularities was more important than sleep duration. And interestingly, if you incorporate sleep duration into the multivariate model, which included the sleep regularity, the sleep irregularity still maintained its significance and was still much more significant than sleep duration.
So this was big news. And there was also a consensus statement, which I'd mentioned, put out by the National Sleep Foundation in 2023. This was before the UK Biobank study, but what they did was they poured through the literature to assess the relationship between sleep regularity and a number of poor clinical outcomes.
And this goes from alertness, autonomic function, health behaviors, which include alcohol consumption, safety behaviors such as drowsy driving, cardiovascular events like hypertension, inflammation, mental health, metabolism, other markers per performance and sleep circadian. So obviously there was a lot of studies.
If I recall correctly, I think it was 180 that were ultimately screened into their strict criteria and they labeled them according to whether there was an association between sleep irregularity and these poor outcomes. And if there was a relationship it was here on the left. If it was neutral, it was kept in the middle.
And if there was an inverse relationship, let's just say if there was any evidence of sleep irregularity showing good outcome, they would've listed here, but we see that there were no studies that fit in that category. It was almost overwhelmingly so. You see that a majority of these studies shows a positive correlation between sleep irregularity and poor outcomes and occasional sort of few neutral studies that were shown here. If you look through the literature and,I identified each of the studies that go into these categories, you could see that sleep irregularity has major clinical correlates. This includes metabolic dysfunction, cardiovascular disease, autonomic function, mental health, cognition, health behaviors, immune function and mortality, which includes all cause cancer and cardiometabolic mortality. So, the relationship is quite extensive in terms of sleep irregularity. This consensus statement that was put out by the National Sleep Foundation was really focused on two major questions.
The first is, is data regularity and sleep timing important for sleep health? Is it important for performance? And the second question was, when sleep is of insufficient duration during this week is catch-up sleep on weekends or non-work days important for health? Now this one's not so much about sleep irregularity, it's much more about sleep indebtedness,
but in terms of addressing this question, they had a panel of 11 panel members. 11 experts. And it's surprising that in terms of addressing these questions, there was almost a majority agreement that there was enough evidence, from the literature to recommend saying that yes indeed, daily regularity and sleep timing is important for health, is important for performance and in fact, this is the quote that came from the conclusion of the consensus statement itself directly from that paper. And it says, the overwhelming body of evidence led the panel to conclude that sleep regularity is important for health and performance.
And the other thing that they said is irregular schedules were not associated with improved outcomes in any study. In other words, irregularity is not good in any circumstance, at least any studies that they found, and based on the preponderance of the evidence currently available, the panel therefore concluded that to the extent that it is feasible, individuals should seek to optimize sleep timing regularity.

Course episodes

Sleep 6.1 Intro to Sleep Regularity

Sleep 6.2 The Clinical Importance of Sleep Regularity

Sleep 6.3 Physiological Mechanisms of Sleep Regularity

Sleep 6.4 Exploring the Factors Influencing Sleep Regularity

Sleep 6.5 Understanding Sleep Regularity Metrics

Sleep 6.6 Future Innovations in Sleep Monitoring