Better sleep may be key to improving cardiometabolic health

Key takeaways:

• Sleep is a necessary component of healthy cardiometabolic function.
• Poor sleep may adversely impact calorie intake, fat distribution and a variety of cardiometabolic parameters.

Adequate sleep duration is essential for overall health, but other components of sleep — a consistent bedtime, uninterrupted sleep, daytime function — can also contribute to cardiometabolic health and associated risk factors.

Taking a multidimensional view of sleep health with targeted goals for each individual may have implications for cardiometabolic health, including diabetes, obesity and a variety of cardiometabolic disorders, according to an American Heart Association scientific statement published in April in Circulation: Cardiovascular Quality and Outcomes. Variations in sleep health have been linked to elevated cardiometabolic risk factors and poorer health outcomes.

“Many components of sleep impact cardiometabolic health through alterations in circadian rhythms,” Marie-Pierre St-Onge, PhD, professor of nutritional medicine and director of the Center of Excellence for Sleep and Circadian Research at Columbia University Irving Medical Center and chair of the American Heart Association scientific statement writing committee, told Healio | Endocrine Today.

With time, “we are learning more about sleep and its impact on cardiometabolic health,” St-Onge said.

Optimal sleep health goes beyond just sleep duration, St-Onge said. According to the scientific statement authors, “conceptualizing sleep as multidimensional emphasizes that sleep is not a unitary physiologic experience, and multiple sleep dimensions affect functioning in various ways.”

“To make strong recommendations, we need to know that the impact of sleep is causal. So we’ve done that quite well in relation to sleep duration. There are a lot of studies that have shown that if you restrict sleep, you increase blood pressure, insulin resistance, inflammation and many other cardiometabolic risk factors,” St-Onge said. “But now we need to know the same for these other components like regularity of sleep, timing of sleep, efficiency, sleep stages and how alterations in those parameters can have an impact on cardiometabolic risk factors.”

The scientific statement classifies eight individual dimensions of multidimensional sleep health. This includes less-discussed and less-studied components that contribute to overall physical and mental health and well-being, according to an American Heart Association press release.

• Sleep duration is defined as number of hours of sleep per night. Multiple studies have shown that less than 7 hours of sleep per night raises the risk for atrial fibrillation, metabolic syndrome and nighttime BP that does not decline during sleep. On the other end, research has linked more than 9 hours of sleep per night to increased risk for metabolic syndrome and death.

• Sleep timing is defined as the time at which sleep is obtained. Research suggests cardiometabolic risk can change based on a person’s sleep timing. For example, a bedtime of midnight or later has been linked to increased risk for overweight or obesity, insulin resistance and hypertension, compared with an earlier bedtime. However, high-quality research on sleep timing and cardiometabolic risk is lacking.

• Sleep regularity/rhythmicity is defined as the stability of an individual’s sleep-wake patterns over time. For example, social jetlag, which occurs when the number of sleep hours changes between workdays and weekends, is associated with a 20% greater risk for overweight or obesity and day-to-day variability is associated with increased risk for cardiovascular disease, hypertension, inflammation and obesity. Irregular sleep timing is linked to higher risk for type 2 diabetes, even in people who had sufficient sleep.

• Sleep satisfaction/quality is defined as an individual’s perception of how well they slept. Research suggests that lower sleep satisfaction is linked to higher BP, coronary heart disease and nighttime BP that does not decline during sleep.

• Alertness/daytime functioning is defined as an individual’s ability to maintain an optimal vigilance throughout the day. Daytime sleepiness has been linked to adverse CV events. Moreover, certain CV risk factors such as obesity, diabetes, smoking and sleep apnea have been linked to increased risk for daytime sleepiness.

• Sleep efficiency is defined as how easily sleep is initiated and maintained. This includes time it takes to fall asleep, how many times an individual wakes throughout the night and the amount of time spent awake after falling asleep. Disturbances in sleep efficiency and continuity are linked to greater risk for myocardial infarction, hypertension and insulin resistance.

• Disturbed sleep is defined as the presence of sleep disorders, such as sleep-disordered breathing and chronic insomnia, as well as use of sleep medications or sleep-enhancing devices.

• Sleep architecture is defined as the amount of time spent in non-rapid eye movement (REM) sleep, which includes light and deep sleep, or REM sleep, which is deep sleep. Research has shown that interruptions in non-REM sleep conferred higher levels of insulin resistance compared with uninterrupted sleep.

“How you sleep affects downstream behaviors that are relevant for cardiometabolic health. If you’re sleeping at different times of the day or if you’re sleeping during the day vs. the night, you may not be as active or be eating at the right time of day when your body is expecting food and able to process and metabolize that food,” St-Onge said. “We also know that some of these sleep factors are related to different cardiometabolic risk factors associated with increased metabolic syndrome and components of metabolic syndrome like blood pressure, triglycerides, glucose and weight status.”

Since sleep health is itself multidimensional, so too should be the treatment once issues arise, such as behavioral interventions for poor sleep efficiency or physiological interventions for abnormal sleep-related breathing, Julio Fernandez-Mendoza, PhD, DBSM, FAHA, the Edward O. Bixler, PhD, Professor of Psychiatry and Behavioral Health, professor of public health sciences and neuroscience & experimental therapeutics at Pennsylvania State University College of Medicine and a member of the American Heart Association scientific statement writing group, said in an interview.

Links between poor sleep and endocrine disorders

Endocrinology societies have not released any large-scale guidelines or scientific statements like the one from the American Heart Association, but evidence is emerging that poor sleep raises risks for conditions such as diabetes and obesity.

Two large cohort studies of participants from the UK Biobank showed that poor sleep is associated with increased risk for development of type 2 diabetes.

In one study of 84,421 adults, published in Diabetes Care in September 2024, compared with people with regular sleep duration as measured by an accelerometer, defined as a standard deviation of 30 minutes or less, people with irregular sleep duration had between 15% and 59% increased risk for new-onset type 2 diabetes, depending on how large the standard deviation of sleep duration was. The association was strongest in people with a low diabetes genetic risk score and in people with longer sleep duration.

In a study of 247,867 adults, compared with those with normal self-reported sleep duration, defined as 7 to 8 hours per day, those getting 5 hours of sleep per day had 16% increased risk for new-onset type 2 diabetes and those getting 3 to 4 hours of sleep per day had 41% increased risk. The difference was present even in people with healthy dietary patterns.

The American Diabetes Association Standards of Care for 2026, released in December, notes that the following populations are at increased risk for development of diabetes: those sleeping less than 7 hours per day, those sleeping more than 9 hours per day, those with poor overall sleep and those with a chronotype with a preference for evenings (ie, going to bed late and getting up late). The Standards recommend that patients with diabetes be counseled to aim to get consistent, uninterrupted sleep, even on weekends. They also recommend that health care professionals screen for sleep disorders and diabetes-related sleep disruptions in people who have prediabetes or diabetes or are at high risk for them.

A study of 14,471 Australian participants aged 15 years or older published in Sleep Medicine in 2023 found that poor sleep duration, defined as less than 7 hours or more than 9 hours per day, was associated with 24% higher odds of obesity compared with good sleep duration, and that poor sleep quality, defined as responding “very bad” or “fairly bad” to the question “‘Overall, how would you rank your sleep during the previous month?”, was linked with 29% higher odds of obesity compared with good sleep quality.

An analysis of the National Health and Nutrition Examination Survey cohorts between 2011 and 2016 (n = 8,748), published in 2023 in Andrology, showed that low sleep duration was associated with high testosterone levels in young men, high sleep duration was associated with low testosterone levels in middle-aged men, and low or high sleep duration was associated with low testosterone levels in middle-aged women. There was no relationship between sleep quality and testosterone levels.

In a meta-analysis of 36 studies including 349,529 women published in Clinical Endocrinology in 2020, compared with women without polycystic ovary syndrome, those with PCOS were more than fourfold likely to have hypersomnia and more than 10-fold likely to have obstructive sleep apnea.

Impact of calorie intake, fat deposits

An avenue by which short sleep duration may have a direct impact on cardiometabolic health may be via changes in calorie intake and fat deposits and distribution.

In a study by Virend K. Somers, MD, PhD, the Alice Sheets Marriott Professor of Cardiovascular Medicine at Mayo Clinic in Rochester, Minnesota, and colleagues published in 2022 in the Journal of the American College of Cardiology, participants assigned to 21 days of inpatient 4-hour sleep restriction consumed significantly more calories, protein and fat compared with individuals who received up to 9 hours of sleep, while energy expenditure remained unchanged. Additionally, participants in the sleep restriction group gained more weight and had increased total abdominal fat, subcutaneous fat and visceral abdominal fat depots, according to the results.

“People who don’t sleep enough tend to eat 300 extra calories a day. The big problem is those extra calories should be deposited in the subcutaneous, relatively safe, fat storage area,” Somers said in an interview. “Sleep-deprived people not only eat more, but they send those calories to the wrong place: the visceral compartment inside the belly. That’s the key driver of cardiometabolic disease: visceral fat. This is an example of how an otherwise healthy, lean young person not sleeping adequately develops poor behavioral choices, eats too much food and excess calories get sent to the wrong storage zone.”

Many factors impact sleep

Many factors can impact nighttime sleep quality, such as apnea, sleeping at different times on a day-to-day basis, or using a cellphone or watching TV before bed, according to Somers.

“The first step is getting a multidimensional sleep history and then addressing those dimensions that are potentially unhelpful,” Somers told Healio | Endocrine Today. “Not eating just before bedtime would be very important. So is avoiding caffeinated beverages and alcohol just before bedtime. If you have reflux, it will wake you from sleep and disrupt your sleep significantly; that’s sometimes a function of eating too much close to bedtime, and sometimes just a function of having reflux. Different people have different behavior patterns in response to exercise. Are you best served by exercising in the morning or do you sleep better if you exercise in the evening?”

Poor sleep can be attributable to other cardiometabolic risk factors, such as BP, weight gain, diabetes, insulin resistance and lipids, Jared A. Spitz, MD, specialty care physician board certified in cardiovascular disease at Inova, told Healio | Endocrine Today. Addressing those factors first may be an opportunity to improve sleep, Spitz said.

“A lot of our problems are upstream related to obesity. If we tackle obesity, we mitigate some of the blood pressure, cholesterol and diabetes issues. Maybe a patient doesn’t need two blood pressure drugs, a cholesterol drug and a diabetes drug if you treat diabetes upstream. Same with sleep,” Spitz said.

Careful management of cardiometabolic therapies could also improve sleep health, Somers said.

“For blood pressure therapy, you don’t want to give people diuretics just before bedtime because they will be up all night using the bathroom,” Somers said. “If they are diabetic and hypoglycemic at night, that can really disrupt sleep and cause other significant problems. If a patient has diabetes and is taking insulin, you want them to be cognizant of how this affects them during sleep. Weight is important because we do know that people with overweight or obesity have poor sleep just on the basis of having excess weight.”

Areas for future research

According to the American Heart Association scientific statement, one barrier to better understanding of the relationship between multidimensional sleep health and cardiometabolic risk is heterogeneity among studies.

“Although it is unknown how all the different dimensions of sleep health interact between each other to predict different outcomes of cardiovascular or metabolic health, there is evidence that insomnia and short sleep interact to predict adverse cardiometabolic health,” Fernandez-Mendoza told Healio | Endocrine Today. “Also, it is unknown to what extent the daytime functioning aspects of sleep health, such as alertness, confer risk of adverse cardiometabolic health outcomes or [whether they] are a sequelae of the interplay between poor nighttime sleep and the development of cardiometabolic morbidity. In addition, although we know the global pathophysiologic mechanisms, those have not been unveiled for each sleep dimension and cardiometabolic health problem.”

Somers said understanding how sleep impacts the endocrine system in addition to more data on the overall “cardiometabolic picture” in the setting of poor sleep are needed. Although increasing sleep duration is generally associated with improved cardiometabolic factors, few data exist on other sleep variables such as regularity, timing and sleep architecture, according to the American Heart Association scientific statement.

“We need to understand what components of sleep we need to ask about and how do those relate to cardiometabolic benefit? Is it sleep duration? That’s easy to target in clinic because we can just talk about the number. But is it sleep architecture, continuity or timing? Do they have different impacts on blood glucose, weight or snacking?” Spitz said. “We know that there are a lot of social determinants of health aspects. This gets to a much broader policy question: Why aren’t people getting good sleep?”

• For more information:
• Julio Fernandez-Mendoza, PhD, DBSM, FAHA, can be reached at jfmendoza@psu.edu.
• Virend K. Somers, MD, PhD, can be reached at somers.virend@mayo.edu.
• Jared A. Spitz, MD, can be reached at endocrinology@healio.com.
• Marie-Pierre St-Onge, PhD, can be reached at ms2554@cumc.columbia.edu.