Too much or too little sleep triggers constipation

Too much or too little sleep triggers constipation in a study of nearly 15,000 adults.

“We thought sleeping too long may be associated with constipation,” said study author Dr Adeyinka Adejumo of North Shore Medical Center in Salem, Massachusetts, US and colleagues. “But we were shocked to find similar results among people who sleep for short durations.”

Constipation rates were significantly lower among normal sleepers (8.3 percent) than short and long sleepers (11.0 percent and 12.5 percent, respectively; p<.0001 for both).

Adejumo said normal sleep duration is thought to be essential for healthy bowel functions, but the impact of limited or excessive sleep on bowel patterns is “poorly understood.”  

To determine if there is a link between the two, Adejumo and team looked at data from 14,590 adults aged 20 years and older who completed questionnaires on sleep and bowel health as part of the National Health and Nutrition Examination Survey (NHANES) from 2005–2010. [DDW 2020, abstract Sa1711]

Sleep was classified into three categories – short (<7 hours), normal (7–8 hours), and long (>8 hours) – based on the US National Sleep Foundation standards and bowel pattern as either normal, constipation, or diarrhoea based on stool formed and bowel movements each week.

No impact on diarrhoea

Short and long sleepers were 61 percent and 38 percent more likely, respectively, to report constipation vs normal sleepers. This was after controlling for demographic, lifestyle, and dietary factors. Interestingly, sleep duration had no impact on diarrhoea.

Similarly, sleep duration did not mediate the relationship between comorbid factors such as overall health, poverty index, obesity, and BMI relevant to constipation in the sensitivity analysis.

The researchers said more studies are warranted to evaluate the physiologic mechanisms driving the impact of sleep duration on bowel function. “This will determine whether sleep disorders, or their underlying causes, affect constipation,” they pointed out.

Global epidemic

Sleepiness and sleeplessness both constitute a global epidemic that threatens health and quality of life. In the US alone, up to 50 percent of Americans suffer from sleep disorders, of which abnormal sleep duration is one of the most common and underdiagnosed, said Adejumo. Constipation and diarrhoea affect almost 10–15 percent of the population, resulting in  significant healthcare burden, but these have not been studied extensively in individuals with suboptimal sleep duration.

Some studies had suggested that bowel contraction slows down considerably during sleep.

“It thus makes sense that sleeping for too long may result in suppressed bowel motility and decreased bowel movement,” Adejumo explained. “However, our results were similar for short sleepers, and we do not know the exact mechanism behind these results.”

“It might be that short sleep resulted in inadequate bowel rest, bowel muscle fatigue, and, subsequently, decreased bowel movement,” he opined. “Or, it may also be that brain-gut signalling pathways are disrupted among short sleepers, as seen among patients with irritable bowel syndrome after a poor night sleep, resulting in greater constipation.”

Hence, clinicians should be aware of the impact of both short and long sleep on constipation, said Adejumo. “Patients who are unable to sleep due to other diseases, including insomnia, disrupted job schedules, or conditions with too long sleep, such as narcolepsy, may additionally suffer from constipation. These patients may need regular evaluation and treatment to improve their discomfort,” he added.