Minimum concurrent sleep, physical activity, and nutrition variations associated with lifeSPAN and healthSPAN improvements: a population cohort study

Background: Sleep, physical activity, and nutrition (SPAN) are key determinants of both life expectancy (lifespan) and disease-free life expectancy (healthspan) yet are often studied and promoted in isolation. This study examined the joint association of these three behaviours with lifespan and healthspan. Methods: Prospective cohort analysis of 59,078 participants from the UK Biobank accelerometry sub-study (median age: 64.0 years; 45.4% male) who wore accelerometers for 7 days and self-reported dietary data. Moderate to vigorous physical activity (MVPA; mins/day) and sleep (hours/day) were calculated using a validated wearables-based algorithm. Diet quality was assessed using a 10-item diet quality score (DQS) based on the consumption of vegetables, fruits, whole grains and refined grains, unprocessed and processed meats, fish, dairy, vegetable oils, and sugary beverages (ranging 0-100, where higher values indicate a higher diet quality). Lifespan and healthspan (defined as years lived free of cardiovascular disease (CVD), cancer, type 2 diabetes (T2D), chronic obstructive pulmonary disease (COPD), and dementia) were estimated across 27 joint tertile combinations of SPAN behaviours and a continuous composite SPAN score using a life table approach. Mortality rates in the life table were adjusted using hazard ratios from a Cox proportional hazards model. The minimum meaningful dose was defined as the smallest combination of behavioural changes associated with a statistically significant gain in lifespan or healthspan. Results: During a median follow-up of 8.1 years, 2,458 deaths, 9,996 incident CVD, 7,681 cancers, 2,971 T2D, 1,540 COPD, and 508 dementia events occurred. Compared with participants in the least favourable tertiles for all SPAN behaviours, those in the optimal tertiles (7.2-8.0 hours/day of sleep; >42 mins/day of MVPA; a DQS of 57.5-72.5) had 9.35 additional years of lifespan (95% CI: 6.67, 11.63) and 9.45 additional years of healthspan (95% CI: 5.45, 13.61). When compared to the 5th percentile for all SPAN behaviours, a minimum combined improvement of 5 mins/day of sleep, 1.9 mins/day MVPA, an extra 5-point increase in DQS (e.g., an additional 1/2 serving of vegetables/day) was associated with 1 additional year of lifespan (95% CI: 0.77, 1.26). For healthspan, a combined improvement of 18.6 mins/day of sleep, 3.4 mins/day of MVPA, and a 21-point diet score increase (e.g. additional 1 cup of vegetables and two servings per week of fish) was associated with 4.0 additional disease-free years (95% CI: 0.27, 8.11). Conclusion: Small, concurrent improvements in sleep, physical activity, and diet quality were associated with substantial gains in lifespan and healthspan. These findings highlight a pragmatic and synergistic approach to improving population health through modest, combined behavioural changes.