Sleeping less than 5 hours increases the risk of NCDs

The study which was published in PLOS Medicine, investigated the influence of sleep duration on the well-being of over 7,000 individuals aged 50, 60, and 70 as part of the Whitehall II cohort study. Researchers explored the correlation between participants’ sleep duration, mortality, and the occurrence of two or more chronic diseases (multimorbidity) such as heart disease, cancer, or diabetes over a 25-year period.

Individuals who reported sleeping 5 hours or less at age 50 were found to be 20% more likely to be diagnosed with a chronic disease and 40% more likely to have 2 or more chronic diseases over 25 years, compared to those with up to 7 hours of sleep. Furthermore, sleeping 5 hours or less at ages 50, 60, and 70 was associated with a 30% to 40% increased risk of multimorbidity compared to those sleeping up to 7 hours.

The study also revealed that a sleep duration of 5 hours or less at age 50 was linked to a 25% increased risk of mortality over the 25-year follow-up. This heightened risk is primarily explained by the fact that insufficient sleep increases the likelihood of developing chronic diseases, subsequently elevating the risk of death.

Lead author Dr. Severine Sabia (UCL Institute of Epidemiology & Health, and Inserm, Université Paris Cité) emphasized the growing challenge of multimorbidity in high-income countries and highlighted the association between short sleep duration and its prevalence. Dr. Sabia recommended promoting good sleep hygiene, ensuring a quiet and comfortable sleep environment, removing electronic devices, and avoiding large meals before bedtime. Physical activity and exposure to light during the day were also suggested to support better sleep.

Study limitations

Researchers used self-reported data on sleep, which is likely to be subject to reporting bias, although using data on 4,000 participants whose sleep was measured via an electronic device confirm the findings.

Meanwhile, data on sleep quality was only available for those aged 60 and 70. Furthermore, the study had an observational design, posing constraints on interpreting results regarding the cause-and-effect associations between short sleep duration and chronic conditions. To address this limitation, recent research has employed Mendelian Randomization (MR), a method that analyzes randomly distributed genetic variants to investigate causal links between factors like short sleep duration and outcomes such as chronic diseases.

A recent study utilizing MR and data from over 350,000 UK participants in fact identified a causal relationship between altered sleep quality due to short sleep or shift work and elevated blood pressure, strengthening the recommendation to get at least 7 hours of sleep every night to preserve health.