How sleep patterns contribute to chronic illness

Sleep is integral to health and is intertwined with health outcomes. To date, most research has honed in on the relationship between sleep duration and chronic illness. Less research, however, has looked at factors such as sleep duration and quality, as well as sleep timing and consistency.

"From a public health perspective, better understanding of how sleep timing and sleep consistency affect health is needed to help inform the development of interventions and public health guidelines for healthy sleep," wrote the authors of a systematic review published in Applied Physiology, Nutrition, and Metabolism

Let’s take a closer look at the relationship between various aspects of sleep and chronic illness.

According to the CDC

The CDC notes that chronic disease has played an increasingly prevalent role in premature death and illness, thus boosting interest in the role that sleep health plays in the treatment of chronic illness.

"Notably, insufficient sleep has been linked to the development and management of a number of chronic diseases and conditions, including type 2 diabetes, cardiovascular disease, obesity, and depression," they wrote.

With respect to heart disease, the CDC explained that sleep apnea appears to share some physiologic characteristics with atherosclerosis. Furthermore, stroke, hypertension, arrhythmias, and coronary artery disease have all been found to be more common in those with disordered sleep. 

Metabolic changes resulting from short-sleep duration have been tied to obesity in laboratory research. Epidemiologic studies have also shown a correlation between short-sleep duration and added body weight in all age groups. In particular, inadequate sleep in children may impact the development of the hypothalamus, which regulates appetite and energy expenditure.

For depression, the relationship between sleep and depression is a little more complex. 

"While sleep disturbance has long been held to be an important symptom of depression, recent research has indicated that depressive symptoms may decrease once sleep apnea has been effectively treated and sufficient sleep restored,” The CDC wrote. “The interrelatedness of sleep and depression suggests it is important that the sleep sufficiency of persons with depression be assessed and that symptoms of depression be monitored among persons with a sleep disorder." 

Lastly, the CDC wrote that insufficient sleep predicts the development of diabetes, adding that sleep duration and quality can predict levels of HbA1C. Optimizing sleep may be helpful in improving serum glucose levels in those with type 2 diabetes.

In other research

Recent studies on the relationship between sleep patterns and chronic disease have come to variable conclusions. Here’s a look at three studies.

In the aforementioned systematic review published in Applied Physiology, Nutrition, and Metabolism, researchers examined the relationships between sleep timing (eg, bedtime/wake-up time, midpoint of sleep); sleep consistency/regularity (eg, intra-individual variability in sleep duration, social jetlag, catch-up sleep); and health outcomes in adults aged 18 years and older.

Social jetlag refers to the time difference between the midpoint of sleep on work nights vs free nights. It is a result of the discrepancy between a person’s own circadian rhythm and daily timing determined by social constraints. 

“[O]ur findings support the notion that later sleep timing and greater sleep variability are both associated with adverse health outcomes,” the authors concluded. “However, the available evidence is unable to provide clear targets to achieve. Thus, earlier sleep timing and regularity in sleep with consistent bedtimes and wake-up times are advised to promote health benefits."

They added: "Regularity in sleep patterns with consistent bedtimes and wake-up times should be encouraged."

In a study published in BMC Psychiatry, researchers in China examined the links between sociodemographic factors, mental health, and chronic disease among 13,768 participants. They found that shorter sleepers had a higher prevalence of chronic conditions such as anemia, gout, hyperlipidemia, and back pain. Moreover, shorter sleepers were likely to have a history of misusing alcohol, as well as being overweight. Conversely, anemia, hyperlipidemia, and low back pain were all risk factors for poor sleep, whereas malignant cancer was a risk factor for longer sleep. The average sleep duration in the study was 6.75 hours.

Researchers published in BMC conducted a community-based cross-sectional study involving 4,150 elderly Chinese participants to determine a relationship between sleep-related variables (eg, nighttime sleep duration, daytime napping, and duration) and chronic disease status (eg, diabetes, cardiovascular diseases, dyslipidemia, cancer, and arthritis). 

Although the researchers did find associations between certain sleep patterns and chronic illness, the relationships were too inconsistent to draw any overall conclusions.

"We found that compared to those with a sleep pattern of ‘short nighttime sleep with daytime napping,’ those with ‘long nighttime sleep without daytime napping’ had higher prevalence of diabetes and lower prevalence of arthritis," they wrote. "Those with ‘long nighttime sleep with daytime napping’ had higher prevalence of diabetes and lower prevalence of cancer.”

For habitual nappers, the participants were grouped by nighttime-daytime duration patterns. Those with “long nighttime sleep with short daytime napping” were more likely to have diabetes, but less likely to have any chronic disease, cancer, or arthritis vs those who had a short nighttime sleep duration combined with long daytime naps.

Importantly, the authors found no association between any type of chronic illness and sleep duration.

Bottom line

Although more research is needed, it appears that adequate sleep, along with sleep consistency, are important factors in the management of chronic illness. Those with healthier sleep patterns, such as going to bed and waking up at consistent times fare better from a health perspective. Consistent and adequate sleep patterns should probably be advised among patients at risk for chronic illness.