It’s safe to say the kids in A Nightmare on Elm Street weren’t getting a quality night’s rest.
All that staying up can really mess with your circadian rhythms, not to mention your blood pressure and mental clarity. However, new research suggests maybe all that running from Freddy Kreuger was doing their long-term health some good.
In a study published on June 29 in the British Journal of Sports Medicine, researchers found that poor sleep and too little physical activity aren’t just bad for health — they are likely connected. Together, both increased the risk of mortality.
Emmanuel Stamatakis is the study’s senior author and a professor at the University of Sydney. The finding, Stamatakis tells Inverse, represents “a great opportunity” for people who don’t sleep well.
“By increasing their physical activity, not only will they enjoy the multitude of direct health benefits of an active lifestyle, but they may also improve their sleep patterns and may even mitigate some of the health risks that come from their poor sleep,” he says.
What's new — Researchers examined data pulled from 380,055 people who participated in the UK Biobank Study, a long-term population study and database. Information was gathered in 2006 and again in 2010.
In 2020, Stamatakis and colleagues looked at which portion of participants had died, the cause of death, and what their sleep and exercise habits had been. They excluded people who already had cancer or heart disease at the start of the study, who had died from Covid-19, or who had any other conditions that could give the results a false spin.
The results suggest an association between a higher risk of mortality, especially from cardiovascular disease and stroke, and:
- Poor sleep
- Limited physical activity
Those who reported less than “moderate to vigorous” exercise, were found to be at a higher risk for cancer, heart disease, and ischemic stroke.
Meanwhile, poor sleep paired with low physical activity seemed to have a “potential synergistic effect” on the risks for cancer and cardiovascular disease, the team reports. When combined, these two factors had more of an effect than the sum of their separate effects.
They also found that people who met the WHO’s recommended daily exercise quota (600 “metabolic equivalent minutes,” which essentially means any kind of exercise beyond sitting) or exceeded it “appeared to eliminate most of the detrimental associations of poor sleep and mortality.”
With enough physical activity, people who got worse sleep could ease that poor sleep’s effect on their health.
The relationship between sleep and exercise
However, few studies have really dug into the effects of both together. Some studies have shown that physical exercise can improve sleep quality, but not necessarily how they interact to affect people’s actual mortality.
“Physical activity is a win-win investment all around.”
But it’s not all sunshine and roses: Sleep and physical activity also have a complex relationship: one can sometimes come at the expense of the other, because of the time constraints that both present. And in some cases of people who get the most exercise (like athletes), too much physical activity has even been shown to negatively affect sleep, and even lead to injuries and infections.
“Good sleep” is also a sticky concept to define. Sleep isn’t just hours spent sleeping (duration) - it’s also sleep quality - affected by things like snoring or frequent wake-ups, and the time of day one tends to sleep (night owls tend to do worse).
To counter this, the authors came up with a new measure that took all three into account.
Why it matters — In recent years, a growing body of research has underscored the crucial roles both sleep and physical exercise play in not just our lives, but also in our mortality. It’s not enough to just eat well or just treat illness with pharmaceuticals. Some people are working longer hours, in increasingly sedentary jobs. The varying pressures to work more and take few (if any) breaks run counter to calls for more sleep and more exercise.
Large-scale studies like this one reinforce the basic human needs for consistent, “quality” sleep, and a body that moves more often than grabbing a coffee or two.
The goal of this study was to see how physical activity interacted with sleep. The authors write:
“Participants who were younger, women, thinner, faced less socioeconomic deprivation, had higher vegetable and fruit intakes, sat less, had no mental health issues, never smoked, were employed in non-shift work, drank less alcohol and had more PA [physical activity], tended to have healthier sleep scores.”
And while we can’t all be young, thin, neuro-typical teetotaling women without socioeconomic deprivation, we can move our bodies more. It’s possible better sleep, and a lower risk of death, could follow.
What's next — When it comes to exercising enough and sleeping well, it’s much easier said than done.
“Physical activity is a win-win investment all around,” says Stamatakis. “For people with more severe sleep problems it will not be necessarily easy to start an exercise plan due to daytime sleepiness or fatigue.”
But Stamatakis adds that less physically active people can start small. For example, one could add 10 to 20 minutes of brisk walking to their schedule, and work up to longer.
“Any activity is fine, as long as they enjoy it and can comfortably fit it in their daily routine,” he explains. “Activities that get them at least slightly breathless would be best.”
This study also sets the stage for further inquiry into the kind of sleep people get and their physical activity in tandem, not just into one or the other. The possibility that they interact in a way that could actually amplify negative, or positive, effects on the body also suggests that interventions to treat one should also consider the other. The authors suggest more “device-based” studies that could track both of these crucial functions of life.
Who knows? Maybe a FitBit could have helped the kids on Elm Street gain some insight into their lifestyle habits, too.
Objectives: Although both physical inactivity and poor sleep are deleteriously associated with mortality, the joint effects of these two behaviours remain unknown. This study aimed to investigate the joint association of physical activity (PA) and sleep with all-cause and causespecific mortality risks.
Methods: 380 055 participants aged 55.9 (8.1) years (55% women) from the UK Biobank were included. Baseline PA levels were categorised as high, medium, low and no moderate-to-vigorous PA (MVPA) based on current public health guidelines. We categorised sleep into healthy, intermediate and poor with an established composited sleep score of chronotype, sleep duration, insomnia, snoring and daytime sleepiness. We derived 12 PA–sleep combinations, accordingly. Mortality risks were ascertained to May 2020 for all-cause, total cardiovascular disease (CVD), CVD subtypes (coronary heart disease, haemorrhagic stroke, ischaemic stroke), as well as total cancer and lung cancer.
Results: After an average follow-up of 11.1 years, sleep scores showed dose-response associations with all-cause, total CVD and ischaemic stroke mortality. Compared with high PA-healthy sleep group (reference), the no MVPA-poor sleep group had the highest mortality risks for all-cause (HR (95% CIs), (1.57 (1.35 to 1.82)), total CVD (1.67 (1.27 to 2.19)), total cancer (1.45 (1.18 to 1.77)) and lung cancer (1.91 (1.30 to 2.81))). The deleterious associations of poor sleep with all outcomes, except for stroke, was amplified with lower PA.
Conclusion: The detrimental associations of poor sleep with all-cause and cause-specific mortality risks are exacerbated by low PA, suggesting likely synergistic effects. Our study supports the need to target both behaviours in research and clinical practice.