Teens who regularly fail to get a good night's sleep may face a higher risk for developing multiple sclerosis (MS) as adults, new research suggests.
“We found that sleeping too little or experiencing poor sleep quality [as a teen] increased the risk of later developing MS by up to 50%,” said study author Dr. Anna Karin Hedström, a senior research specialist in the clinical neuroscience department at the Karolinska Institute in Stockholm, Sweden.
MS is a disabling neurodegenerative disease that targets the body's central nervous system, essentially short-circuiting communication between the body and brain. According to the U.S.-based National Multiple Sclerosis Society, the disease affects roughly 2 million Americans.
The MS Society notes that sleep issues -- including insomnia, sleeping too much, narcolepsy and/or sleep apnea -- are more common among those who have MS, compared with healthy peers.
Difficulty sleeping, MS Society experts note, may source back to the physical limitations brought on by MS. Those can include increased fatigue and reduced physical activity capacity, alongside chronic symptoms such as restless legs, pain, body temperature fluctuations and urinary/bowel discomfort.
MS can also take an emotional toll that undermines sleep, due to an increase in stress or anxiety and a heightened risk for depression.
But might poor sleep also perhaps precede the onset of MS, upping long-term risk in the process?
To look into the possibility, the research team focused on nearly 2,100 adult MS patients and about 3,200 randomly selected healthy adult peers up to the age of 70.
Participants completed adolescent sleep questionnaires at some point between 2005 and 2018.
The questionnaires focused on sleep habits and quality back when participants were between 15 and 19 years old, when none had been diagnosed with MS.
For example, all were asked to recall how long they slept on work and/or school days versus how long they slept on weekends and days off. “Short sleep” was characterized as under seven hours of sleep a night, while "adequate sleep" was defined as between seven to nine hours. Staying in bed 10 hours or more was pegged as "long sleep."
All were also asked to rank the quality of their sleep on a scale of 1 to 5 (with 5 the best).
Among those who eventually developed MS, the average age of diagnosis was 35.
And after crunching the numbers, the team ultimately determined that regularly experiencing "short sleep" was linked to a 40% higher risk for developing MS as an adult, when compared with routinely getting "adequate sleep."
The finding held up even after accounting for factors that can influence sleep habits, such as body mass index -- a marker for obesity -- and smoking.
By contrast, “long sleep” was not linked to a higher risk for MS. Nor was routinely staying up later on days off, so long as overall sleep duration and quality remained adequate.
On the other hand, those who said the quality of their teen sleep was generally poor were found to face a 50% higher risk for developing the disease.
Still, even if MS risk is higher among those whose teenage sleep habits were less than ideal, “the prevalence of MS [remains] very low, far less than 1 in 1,000," said the study's lead author, Torbjörn Åkerstedt.
"So one should avoid alarmism," added Åkerstedt, past president of the European Sleep Research Society and a Karolinksa Institute professor of clinical neuroscience.
So what's going on? The study team pointed to prior research indicating that a lack of sleep and poor sleep quality are associated with systemic inflammation and impaired immune function. Over time, both can increase vulnerability to chronic health issues and serious disease.
The upshot, said Hedström, is that “sufficient restorative sleep -- which is needed for adequate immune functioning -- is important.”
Kathy Zackowski, the MS Society's associate vice president of research, cautioned that the investigation relied entirely on people's recollections of past sleep patterns, sometimes decades earlier. “We will need more objective research to look into this,” she said.
“At the same time, there's really been nothing, no research at all, around sleep and MS among adolescents,” Zackowski acknowledged. “So this work really fills a need.”
She added the findings make sense. "Not only that the number of hours of sleep matters but also that sleep quality matters, too, particularly among adolescents," Zackowski said. "They're going through a lot of emotional changes from hormones and tons of brain growth, since the brain doesn't finish growing until 25 or 26. All of that is pretty draining on the nervous system, to build all that hardware that we need to get us through life.”
“And sleep,” Zackowski agreed, “is known to be restorative.”
The findings appear online Jan. 23 in the Journal of Neurology Neurosurgery & Psychiatry.
There's more on multiple sclerosis at the U.S.-based National Multiple Sclerosis Society.
SOURCE: Anna Karin Hedström, MD, PhD, senior research specialist, department of clinical neuroscience, Karolinska Institute, Stockholm, Sweden; Torbjörn Åkerstedt, PhD, professor, department of clinical neuroscience, Karolinska Institute, Stockholm, Sweden, and past president, European Sleep Research Society; Kathy Zackowski, PhD, OTR, associate vice president, research, National MS Society, New York City; Journal of Neurology Neurosurgery & Psychiatry, Jan. 23, 2023