According to a new scientific statement from the American Heart Association, published in Circulation: Cardiovascular Quality and Outcomes, sleep health includes various components such as sleep duration, time taken to fall asleep, sleep satisfaction, daytime functioning, and consistency of sleep patterns. Addressing these diverse aspects of sleep may help reduce the risk of cardiometabolic conditions.
The statement reviews emerging evidence linking sleep to physical and mental well-being, as well as cardiometabolic factors such as body fat, blood pressure, blood sugar, and cholesterol levels. It outlines six primary dimensions of sleep health:
- Sleep Duration: Adults typically need 7 to 9 hours of sleep per night. Sleeping fewer than 7 hours is linked to increased risks of atrial fibrillation, cardiometabolic syndrome, and insufficient nighttime blood pressure decline. Sleeping more than 9 hours has also been associated with higher risks of cardiometabolic syndrome, arterial stiffness, stroke, and cardiovascular-related death.
- Sleep Continuity: This refers to how uninterrupted one’s sleep is. Poor sleep continuity—characterised by long time to fall asleep, frequent night awakenings, or sleep apnoea—is associated with increased risks of heart attack, atrial fibrillation, hypertension, and insulin resistance.
- Sleep Timing: The habitual time a person goes to bed influences cardiometabolic risk. Later bedtimes, especially after midnight, are associated with higher risks of obesity, insulin resistance, and elevated blood pressure. Research in this area is still evolving.
- Sleep Satisfaction: An individual’s perception of their sleep quality plays a role in overall health. Poor sleep satisfaction has been linked to stiffer arteries, coronary heart disease, and non-dipping nighttime blood pressure.
- Sleep Regularity: Irregular sleep schedules—such as varying sleep times between weekdays and weekends—have been associated with obesity, Type 2 diabetes, high blood pressure, inflammation, and increased cardiovascular risk. More consistent sleep-wake patterns are linked to significantly lower risks of cardiovascular-related death.
- Daytime Functioning: The ability to stay awake and alert during the day is an important marker of sleep health. Excessive daytime sleepiness is tied to greater risk of cardiovascular disease and mortality. It’s also associated with depression, obesity, smoking, and sleep apnea—while weight loss may improve daytime alertness.
- Sleep Architecture: Sleep occurs in cycles, moving through non-REM (light and deep sleep) and REM stages. Disruptions, especially to deep (slow-wave) sleep, are linked to greater insulin resistance. These stages are typically assessed through EEG monitoring.
The statement also highlights disparities in sleep health driven by social and environmental factors. Over 300 studies have found that lower socioeconomic status is consistently associated with poorer sleep. Factors such as noise, air and light pollution, and neighbourhood safety all influence sleep quality.
People from historically underrepresented racial and ethnic groups—particularly Black adults—experience disproportionately poorer sleep health, including shorter sleep duration, more irregular schedules, and higher levels of daytime sleepiness. These disparities are seen across all age groups and can perpetuate broader health inequities.
Healthcare providers are encouraged to ask patients specific questions about sleep—such as how long it takes them to fall asleep, how often they wake at night, and how tired they feel during the day—to better evaluate overall sleep health. Recording these insights in medical records may prompt further assessment and ensure that sleep is considered in the context of other health conditions and medications.
Although sleep duration is currently the only sleep component included in the American Heart Association’s Life’s Essential 8 cardiovascular health metrics, there is a growing recognition that other dimensions are just as important. Wearable devices can help track sleep duration, but improved methods are needed to reliably measure other components like sleep regularity and continuity.
Source: American Heart Association
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