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With disordered sleep spiking during the pandemic, new findings about potentially serious detrimental health effects are prompting even greater concern than usual. Determining the precise number of hours of sleep necessary for good health can be challenging, but a recent study from the United Kingdom and France suggests a possible threshold.
In the study, nearly 8000 civil servants in the United Kingdom reported their nightly amount of sleep every 4-5 years for the next 25 years, beginning at age 50 years. Study participants were free of chronic disease at age 50 and were mostly male (67.5%) and White (90%). Research showed that the 30% increased risk for chronic illness among those who slept ≤ 5 hours at age 50 years (hazard ratio [HR] , 1.30; 95% CI , 1.12 -1.50; P < .001) increased to 32% by age 60 years (HR , 1.32; 95% CI , 1.13 -1.55; P < .001) and to 40% by age 70 years (HR , 1.40; 95% CI , 1.16 -1.68; P < .001). The chronic conditions for which risk increased included diabetes, cancer, coronary heart disease, stroke, heart failure, chronic obstructive pulmonary disease, chronic kidney disease, liver disease, depression, dementia, Parkinson’s disease, and arthritis.
Findings like these are what encouraged the American Heart Association to include sleep duration as “an essential component for ideal heart and brain health” on its updated checklist, now called Life’s Essential 8. A study compared four versions of what was previously called the Life’s Simple 7 checklists, which included sleep in relation to cardiovascular disease (CVD) risk. Study participants who scored in the highest tertile of the cardiovascular health checklists that included sleep had up to a 47% lower CVD risk. Sleeping 7 hours or more but less than 9 hours nightly was considered “ideal,” according to the study. “Our study is the first to show that sleep metrics add independent predictive value for CVD events over and above the original seven cardiovascular health metrics,” lead author Nour Makarem, PhD, told theheart.org | Medscape Cardiology.
Negative associations with too much sleep have also been noted recently. Results from a population-based study of almost 2000 older adults showed that the risk for dementia was 69% higher in those who slept more than 8 hours daily vs 7-8 hours daily. Furthermore, findings showed that the risk was twice as high for those who went to bed before 9 PM vs at 10 PM or later. The associations were most pronounced in those aged 60-74 years and in men. Every 1-hour advance in bedtime was associated with a 25% increased risk for dementia (95% CI, 1.03-1.53). Every 1-hour advance in bedtime and mid-sleep time was associated with an adjusted HR of 1.27 (95% CI, 1.01-1.59) and 1.49 (95% CI, 1.05-2.12), respectively.
The quest for more and better sleep has led to various interventions. A recent study found that a weighted blanket of approximately 12% body weight prompted the release of higher concentrations of melatonin, compared with a lighter blanket of only about 2.4% of body weight. The small, in-laboratory crossover study found that use of a weighted blanket increased melatonin in the saliva by around 30%. The study involved a total of 26 healthy volunteers, 15 men and 11 women, none of whom had any sleep issues. Two nights were tested: one in which the weighted blanket was used and the second during which the lighter blanket was used. On test nights, lights were dimmed between 9 PM and 11 PM, and participants used a weighted blanket covering the extremities, abdomen, and chest 1 hour before and during 8 hours of sleep. The average increase in salivary melatonin concentrations was greater under weighted-blanket conditions at 6.6 pg/mL compared with 5.0 pg/mL during the lighter-blanket session (P = .011). Oxytocin rose by about 315 pg/mL initially, but this was only transient. Over time, no significant difference in oxytocin levels was observed between the two blanket conditions.
From investigations into ways to get the right amount of quality rest to new findings that suggest just how important that can be in avoiding certain health conditions, news about sleep resulted in this week’s top trending clinical topic.