; and (2) continue implementation of the NIH Sleep Disorders Research Plan across all institutes and centers of the National Institutes of Health to improve treatment and prevention of sleep health disparities. (b) Required research activities In conducting or supporting research relating to sleep and circadian rhythm, the Director of the National Heart, Lung, and Blood Institute shall— (1) advance epidemiology and clinical research to achieve a more complete understanding of disparities in domains of sleep health and across population subgroups for which cardiovascular and metabolic health disparities exist, including— (A) prevalence and severity of sleep apnea; (B) habitual sleep duration; (C) sleep timing and regularity; and (D) insomnia; (2) develop study designs and analytical approaches to explain and predict multilevel and life-course determinants of sleep health and to elucidate the sleep-related causes of cardiovascular and metabolic health disparities across the age spectrum, including such determinants and causes that are— (A) environmental; (B) biological or genetic; (C) psychosocial; (D) societal; (E) political; or (F) economic; (3) determine the contribution of sleep impairments such as sleep apnea, insufficient sleep duration, irregular sleep schedules, and insomnia to unexplained disparities in cardiovascular and metabolic risk and disease outcomes; (4) develop study designs, data sampling and collection tools, and analytical approaches to optimize understanding of mediating and moderating factors, and feedback mechanisms coupling sleep to cardiovascular and metabolic health disparities; (5) advance research to understand cultural and linguistic barriers (on the person, provider, or system level) to access to care, medical diagnosis, and treatment of sleep disorders in diverse population groups