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, finds a new study led by scientists from University College London (UCL).
The research analyzed the impact of sleep duration on the health of more than 7,000 men and women at the ages of 50, 60, and 70, from the Whitehall II cohort study. The study was published on October 18 in PLOS Medicine.
Scientists investigated the relationship between how long each participant slept and their mortality, as well as whether they had been diagnosed with two or more chronic diseases (multimorbidity) – such as heart disease, cancer, or diabetes. This was done over the course of 25 years.
“This research adds to a growing body of research that highlights the importance of getting a good night’s sleep.” — Jo Whitmore
Compared to people who slept for up to seven hours, individuals 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.
Furthermore, 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 people who slept for up to seven hours.
Sleep duration of five hours or less at age 50 was associated with a 25% increased risk of mortality over the 25 years of follow-up, according to the research results. This 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.
Lead author, Dr. Severine Sabia (UCL Institute of Epidemiology & Health, and Inserm, Université Paris Cité) said: “Multimorbidity is on the rise in high-income countries and more than half of older adults now have at least two chronic diseases. This is proving to be a major challenge for public health, as multimorbidity is associated with high healthcare service use, hospitalizations and disability.
“As people get older, their sleep habits and sleep structure change. However, it is recommended to sleep for 7 to 8 hours a night— as sleep durations above or below this have previously been associated with individual chronic diseases.
“Our findings show that short sleep duration is also associated with multimorbidity.
“To ensure a better night’s sleep, 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.”
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.
Jo Whitmore, senior cardiac nurse at the British Heart Foundation said: “Getting enough sleep allows your body to rest. There are a host of other ways that poor sleep could increase the risk of heart disease or stroke, including by increasing inflammation and increasing blood pressure.
“This research adds to a growing body of research that highlights the importance of getting a good night’s sleep.”
Researchers used self-reported data on sleep, which is likely to be subject to reporting bias. However, the findings were confirmed using data on 4,000 participants whose sleep was measured via an electronic device.
Meanwhile, data on sleep quality was only available for those aged 60 and 70.
The Whitehall II study only involves members of the civil service, who were all employed when recruited to the study and likely to be healthier than the general population.
Reference: “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” by Séverine Sabia, Aline Dugravot, Damien Léger, Céline Ben Hassen, Mika Kivimaki and Archana Singh-Manoux, 18 October 2022, PLOS Medicine.
The research was funded by the National Institute on Aging, part of NIH, UK Medical Research Council, the British Heart Foundation, and Wellcome.