‘Early birds’ have significantly lower ALS risk than ‘night owls’: Study
People who are more physically active also less likely to develop disease
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- Early birds and people who get 6 to 8 hours of sleep per night linked to lower ALS risk.
- Higher physical activity is also associated with reduced ALS risk.
- Healthy sleep and an active lifestyle may be potential strategies to reduce ALS risk.
Early birds — people with a natural tendency to wake up and go to sleep at earlier times — are significantly less likely to develop amyotrophic lateral sclerosis (ALS) than night owls, whose natural preference is to wake up and go to sleep at later times, according to a new study in China.
ALS risk is also reduced among people who sleep between 6 and 8 hours a night and those who engage in more physical activity.
The study, “Sleep, Physical Activity, and Incident Amyotrophic Lateral Sclerosis: A Large Prospective Cohort Study of Over 500,000 Participants,” will be presented at this year’s American Academy of Neurology (AAN) Annual Meeting, which will be held in April in Chicago and online.
“Our study found a sleep schedule that better matches daylight hours and more physical activity were related to a lower risk of ALS,” Hongfu Li, MD, PhD, co-author of the study at Zhejiang University in China, said in an AAN press release.
Sleep habits, exercise routines can profoundly influence health
ALS is a neurodegenerative disease in which motor neurons, the nerve cells that control movement, gradually sicken and die. The causes of ALS are not fully understood — genetic factors underlie some cases, but environmental exposures and lifestyle habits have also been identified as potential ALS risk factors.
Among potential lifestyle risk factors, sleep habits and exercise routines can profoundly influence health. Previous studies have linked both poor sleep and a more sedentary lifestyle with a higher risk of certain neurodegenerative diseases such as Alzheimer’s, but it hasn’t been clear if these associations also exist for ALS.
“Previous research suggests better sleep and more physical activity may reduce the risk of some neurodegenerative diseases, but results for ALS have been mixed,” Li said.
To find out more, Li and colleagues analyzed data from more than 500,000 people, with a mean age of 56.5 years, who participated in a long-term health study. Over a median follow-up of nearly 14 years, 675 participants (0.14%) were diagnosed with ALS.
At the start of the long-term study, participants had completed questionnaires assessing their sleep habits and physical activity.
For sleep, 277,620 participants were considered early birds, meaning they had a morning chronotype, and 166,361 were night owls, with an evening chronotype. A third group of 58,298 participants were excluded because their chronotype could not be determined.
The researchers conducted statistical analyses to compare ALS risk between early birds and night owls, accounting for factors such as age, sex, and body mass index. Results showed that such risk was 20% lower in early birds.
Analyses also indicated a “U-shaped” association between ALS risk and overall sleep duration: individuals who reported between six and eight hours of sleep per night had lower ALS risk than those who reported either more or less sleep per night.
People who are more physically active 26% less likely to develop ALS
The researchers also assessed the link between ALS risk and physical activity habits using metabolic equivalents (METs), a standard way of estimating energy use. One MET represents the amount of energy a person uses while at rest. Activities are assigned higher MET values based on the additional energy they require compared with resting.
In general, vigorous activities such as running or fast cycling are assigned 8 METs, moderate-intensity activities like performing household chores or gardening are assigned 4 METs, and walking is assigned 3.3 METs. Researchers then multiply these values by the number of minutes spent doing each activity to calculate total energy expenditure.
While more research is needed to explore these associations further, promoting healthy lifestyle behaviors may represent a potential strategy for reducing the risk of ALS.
In this study, participants’ average physical activity level was 2,645 METs minutes per week.
After adjusting for other factors, the team found that individuals with at least 600 MET-minutes of activity per week were 26% less likely to develop ALS than those with lower activity levels. Of note, 600 MET-minutes is equal to about 75 minutes of vigorous exercise or about three hours of low-intensity exercise.
The researchers stressed that this study examined only statistical correlations, and these associations don’t prove a cause-and-effect relationship. Also, almost all participants were white, so more work is needed to validate the findings in people of other backgrounds. Still, the data indicate that promoting healthy sleep and an active lifestyle may help reduce ALS risk, the scientists said.
“While more research is needed to explore these associations further, promoting healthy lifestyle behaviors may represent a potential strategy for reducing the risk of ALS,” Li said.
