AHA statement highlights risk factors, interventions for irregular circadian rhythm
Timing and regularity of sleep, meal timing, and timing of physical activity, all hold potential to improve misaligned circadian rhythms, according to a recent statement form the American Heart Association (AHA).
A scientific statement from the American Heart Association outlines key behavioral factors that affect circadian rhythm and details the association between circadian and cardiometabolic health.
Disease, light exposure patterns, rotating or night shift work, and mistimed sleep, meals, or exercise can all disrupt circadian rhythms, notes the statement, which was published by Circulation on Oct. 28.
Natural sunlight in the morning is “essential for synchronizing circadian rhythms to the light–dark cycle, promoting alertness, and maintaining a healthy sleep–wake cycle,” the authors said. They recommend against exposure to bright light in the evening, particularly short-wavelength (blue–green) light, in part because it suppresses melatonin secretion.
Studies also show irregular eating patterns, such as late-night eating and prolonged eating windows, are associated with a greater risk of obesity, type 2 diabetes, and cardiovascular disease, whereas eating early in the day has been associated with improved cardiometabolic health, according to the statement.
Research indicates exercise helps synchronize peripheral clocks in cells throughout the body (particularly in cardiovascular and metabolic systems) and impacts the central circadian clock (the suprachiasmatic nucleus in the hypothalamus), the experts said.
What's more, because circadian rhythms regulate metabolism, appetite, and energy expenditure, “circadian disruption has been associated with weight gain and obesity,” the authors wrote. More rhythmic lifestyle behaviors are associated with a lower risk of glycemic dysregulation and type 2 diabetes, they added.
Circadian disruption also affects hypertension risk. Research has shown the circadian rhythm of blood pressure is altered in patients with chronic kidney disease, suggesting “circadian disruption may be particularly relevant to cardiovascular–kidney–metabolic health, which is associated with cardiovascular disease incidence and mortality risk,” the statement said.
Individuals working nontraditional schedules, such as shift workers, are disproportionately affected by circadian misalignment, the authors added. Interventions that focus on the timing of therapy (i.e., chronotherapy), hold potential to improve circadian and cardiovascular health according to the statement. Appropriately timed melatonin is one option, but the experts urged caution as the effects of the supplement on cardiometabolic health are poorly understood.
Regulating light exposure is another potential solution. Time-restricted eating may help maintain alignment of peripheral clocks to the central clock, while the timing of physical activity could potentially benefit those with circadian misalignment, the statement said.
Overall, the statement called for more research on effective interventions for circadian health and to establish an unequivocal link between circadian disruption and cardiometabolic disease. Future developments in metabolomics, wearable technologies, and artificial intelligence may help researchers more precisely assess circadian rhythms, the authors concluded.