The healthy sleep includes multiple components, such as the number of hours of sleep per night, the time it takes to fall asleep, and daytime functioning. Addressing these different dimensions of sleep can help improve cardiometabolic health and related risk factors, according to a new statement published in ‘Circulation: Cardiovascular Quality and Outcomes’.
This new work describes multiple components of sleep health, such as duration, continuity, rhythm, satisfaction, regularity, and daytime functioning. The scientific statement also reviews the latest evidence on the relationship between sleep and various cardiometabolic health factors, such as body fat, blood sugar, cholesterol, and blood pressure, and how healthy sleep positively impacts physical health and mental well-being.
"Most adults need between 7 and 9 hours of sleep each night, and suboptimal sleep increases the risk of cardiovascular diseases, along with the risk of cognitive decline, depression, obesity, as well as high blood pressure, blood sugar, and cholesterol levels," said the chair of the writing group for the scientific statement, Marie-Pierre St-Onge.
"However, there is increasing evidence that sleep health goes beyond the number of hours slept each night," the researcher added.
SLEEP AND CARDIOMETABOLIC HEALTH
The first component analyzed is sleep duration. The most recent data from multiple studies indicate that sleeping less than 7 hours per night increases the risk of atrial fibrillation, cardiometabolic syndrome, and high blood pressure. On the other hand, sleeping too much or more than 9 hours per night is also associated with a higher risk of cardiometabolic syndrome, arterial stiffness, stroke, or death from heart disease or stroke.
The second point analyzed is sleep continuity, that is, the proportion of time spent asleep. Disruptions in sleep continuity have been associated with a higher risk of atrial fibrillation, heart attack, high blood pressure, or increased insulin resistance.
The third component reviewed is the time at which a person usually goes to sleep during a 24-hour period. High-quality research on bedtime is limited; however, data suggest that suboptimal bedtime may be associated with an increased risk of cardiovascular diseases. Going to bed at midnight or later, compared to before midnight, has been associated with a higher risk of overweight or obesity, insulin resistance, and high blood pressure.
The fourth point is satisfaction with sleep, the perception a person has of their sleep experience. A combined analysis of recent research indicates that lower satisfaction with sleep is associated with higher blood pressure, stiff and less flexible arteries, coronary heart disease, and nighttime blood pressure that does not decrease.
On the other hand, the fifth point is sleep regularity: A large-scale study from the UK Biobank linked an increased risk of type 2 diabetes even in people who slept enough, with the highest risk among those who slept very little and had very irregular sleep patterns.
The sixth point analyzed is daytime functioning related to sleep, that is, a person’s ability to remain alert and awake during the day. Excessive daytime sleepiness is associated with cardiovascular diseases, coronary heart disease, strokes, and death from both cardiovascular diseases and any other cause. Some cardiovascular risks, such as obesity, type 2 diabetes, depression, smoking, and obstructive sleep apnea, were associated with a higher risk of daytime sleepiness, while weight loss appeared to reduce excessive daytime sleepiness.
Finally, the seventh point analyzed is sleep architecture, which refers to the sleep stages the body typically goes through while sleeping. Sleep is divided into two categories: non-rapid eye movement (Non-REM) sleep, which includes light and deep sleep stages, and rapid eye movement (REM) sleep, the deepest stage of sleep. An analysis of combined studies found that the disruption of Non-REM sleep, also known as slow-wave sleep, led to higher levels of insulin resistance compared to uninterrupted sleep.
DIFFERENCES IN SLEEP HEALTH
The statement also addresses differences in sleep health among individuals affected by adverse social factors for health. A recent review of over 300 studies found consistent associations between lower socioeconomic status and suboptimal sleep health.
Social and environmental factors, including home and neighborhood characteristics, such as light, air, and noise pollution, and safety, also contribute to differences in one or more components of sleep health.
Compared to the non-Hispanic white population, individuals belonging to historically underrepresented racial and ethnic groups sleep less and are more likely to experience poorer sleep continuity, less satisfaction with sleep, later bedtimes, more irregular sleep, greater daytime sleepiness, and a higher incidence of sleep disorders. These differences are observed throughout life and persist over time, with black adults having the poorest sleep health among all individuals.
"It is important to know that each individual has different sleep experiences, and these differences can contribute to other health inequalities," says St-Onge, adding that "including different components of sleep in conversations with patients provides essential information that can help healthcare professionals improve care."
MORE RESEARCH IS NEEDED TO OPTIMIZE SLEEP HEALTH
Awareness of the importance of sleep is increasing; however, experts point out that more research is needed on the various dimensions of sleep health so that doctors can support patients in promoting healthy sleep and improving health.
Although there are numerous smartwatches and other personal devices to track the amount of time spent asleep per night, advances are needed in evaluating other dimensions of sleep.
Sleep is one of the health metrics highlighted in Life’s Essential 8, the American Heart Association’s measures for optimal cardiovascular health. By incorporating sleep into the Life’s Essential 8 score, the only measure for sleep is its duration (number of hours per night) because there are not enough validated research to confirm how to evaluate other components of sleep.
According to some research studies, poor sleep health contributes to adverse cardiovascular outcomes. Therefore, evidence from clinical trials is needed to confirm that improving sleep health leads to better cardiometabolic health.
