- The relationship between sleep and the risk of developing obesity or type 2 diabetes is unclear, but it is thought to be a bidirectional relationship.
- Study reveals that varying the amount of sleep each night could lead to diabetes risk.
- A new analysis of UK Biobank data shows that greater variability in sleep duration is associated with increased diabetes risk, especially in people who sleep longer and have a lower genetic risk score for diabetes.
Irregular sleep has been linked to the risk of type 2 diabetes, but this effect was attenuated when the data was adjusted to account for obesity, comorbidities and lifestyle factors.
Researchers from Boston, Massachusetts, and Manchester, UK, found that people who had the most variation in their nightly sleep duration were 59% more likely to develop diabetes over a 7.5-year follow-up period than those whose sleep patterns were the most stable.
The result is Diabetes Care.
To investigate the link between irregular sleep and diabetes risk, the researchers used data from UK Biobank and obtained permission to use the data of 84,421 participants for the study. Sleep data was available because participants had been asked to wear an accelerometer, a device that captures activity levels, for seven days at some point between 2013 and 2015. Accelerometers are very similar to fitness watches.
The average age of participants was 62 years old, and the researchers also used personal genetic data held in Biobank to calculate a polygenic risk score for diabetes using known genetic risk variants for diabetes.
The researchers found that participants whose sleep times deviated 31 to 45 minutes from the average had a 15% higher risk of diabetes compared with those whose sleep times were within 30 minutes. Participants with the greatest variability, whose sleep times deviated by 91 minutes or more, had a 59% increased risk after adjusting for age, sex, and race.
The researchers also analyzed the difference between those who slept more than 60 minutes and those who slept less than 60 minutes and found that those with a difference of more than 60 minutes had a 34% increased risk, but after adjusting the data to account for lifestyle, comorbidities, environmental factors and obesity, the risk reduced to 11%.
97% of this group were white and over 45% were university graduates, neither of which are representative of the UK population as a whole.
The authors did not explore the mechanisms underlying the association they found in this prospective cohort study, but explained that it may be because irregular sleep patterns disrupt circadian rhythms, which they suggested could interfere with glucose metabolism and lead to reduced insulin sensitivity.
Because of growing evidence that sleep variation can affect metabolic health, the researchers investigated the impact of sleep variation on diabetes risk. Sleep duration, sleep quality, and other sleep disturbances have been linked to diabetes risk in previous studies.
Sudha Tharavajra, MD“The results are surprising,” said a neurologist and sleep medicine physician at UTHealth Houston who was not involved in the study. Today's Medical News:
“For both clinical and research purposes, we found that sleep disorders alter hormonal pathways. During sleep, the entire endocrine axis, a pathway that encompasses all hormonal functions, cycles. Hormones that are not needed during sleep because activity is low, such as insulin and steroids, typically decrease. Their levels rise in the morning to meet activity demands. Sleep disorders lead to poor glucose and fat utilization.”
It's not clear if one is causing the other, she explained, and the problem could go both ways.
“There is a wealth of research showing that both obesity and diabetes are associated with sleep disorders. Looking at the bigger picture, sleep disorders are associated with the overall metabolic inefficiency that underlies both diabetes and obesity. This relationship is multifactorial and bidirectional, so sleep disorders may increase the risk of diabetes and obesity. These two conditions may also contribute to sleep disorders.”
— Sudha Tharavajra, MD
Researchers have previously studied the impact of circadian rhythms on the risk of type 2 diabetes. Annals of Internal MedicineThey looked at the Nurses' Health Study II and found that “night types” were more likely to develop type 2 diabetes than “morning types.”
Chronotype – whether a person feels the need to go to bed early or wake up late – is linked to their circadian rhythm, which describes their body's internal clock and is thought to be affected by light levels, among other things.
The researchers also found that “night owls” were more likely to report unhealthy lifestyle habits. When they adjusted the data to account for these factors, the effect of chronotype was still present, but weaker.
Although the study did not clarify the underlying mechanisms, it confirmed the importance of healthy habits in preventing type 2 diabetes. Dr. Becca Ann Krukowski“The study is a step forward for the public health sciences community,” said Professor of Public Health Sciences at the University of Virginia School of Medicine, who was not involved in the study. MNT.
“Maintaining healthy habits, such as regular exercise and a healthy, balanced diet as well as regular sleep, contributes to overall health and may help prevent type 2 diabetes,” she said.