Approximately one third of human life is devoted to sleep, emphasizing the vital role of sleep in several physiological functions essential for health. There is also consistent evidence of an association of sleep duration with chronic diseases, such as cardiovascular disease (CVD) and cancer, and with mortality, although there remain a number of outstanding questions regarding the nature of this association.
It is unclear how sleep duration affects trajectories from a healthy state, to 1 or more chronic diseases, and subsequent mortality. Several biological mechanisms have been proposed to explain the role of short sleep duration in disease onset but the role of long sleep is less well understood. The observed risk of chronic conditions among long sleepers could be due to preexisting health conditions or, alternatively, reflect non-restorative sleep that then affects risk of subsequent disease.
Getting less than five hours of sleep in mid-to-late life could be linked to an increased risk of developing at least two chronic diseases
New study analysed the impact of sleep duration on the health of more than 7,000 men and women at the ages of 50, 60 and 70. Researchers examined the relationship between how long each participant slept for, mortality and whether they had been diagnosed with two or more chronic diseases (multimorbidity), such as heart disease, cancer or diabetes, over the course of 25 years.
People who reported getting five hours of sleep or less at age 50 were 20% more likely to have been diagnosed with a chronic disease and 40% more likely to be diagnosed with two or more chronic diseases over 25 years, compared to people who slept for up to seven hours.
Additionally, sleeping for five hours or less at the age of 50, 60, and 70 was linked to a 30% to 40% increased risk of multimorbidity when compared with those who slept for up to seven hours.
Researchers also found that sleep duration of five hours or less at age 50 was associated with 25% increased risk of mortality over the 25 years of follow-up — which can mainly be explained by the fact that short sleep duration increases the risk of chronic disease(s) that in turn increase the risk of death.
As part of the study, researchers also assessed whether sleeping for a long duration, of nine hours or more, affected health outcomes. There was no clear association between long sleep durations at age 50 and multimorbidity in healthy people.
However, if a participant had already been diagnosed with a chronic condition, then long sleep duration was associated with around a 35% increased risk of developing another illness. Researchers believe this could be due to underlying health conditions impacting sleep.
According to the results of this study, it is important to promote good sleep hygiene, such as making sure the bedroom is quiet, dark and a comfortable temperature before sleeping. It’s also advised to remove electronic devices and avoid large meals before bedtime. Physical activity and exposure to light during the day might also promote good sleep.
Séverine Sabia, Aline Dugravot, Damien Léger, Céline Ben Hassen, Mika Kivimaki, Archana Singh-Manoux (October 18, 2022). Association of sleep duration at age 50, 60, and 70 years with risk of multimorbidity in the UK: 25-year follow-up of the Whitehall II cohort study. PLOS Medicine. Retrieved from : https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1004109
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