Smart ring-based assessment of physical activity intensity and sleep disturbances in older adults with mild cognitive...

Sleep disturbance is common in older adults with mild cognitive impairment (MCI) and is linked to poorer cognitive and overall health, but prior evidence is mixed and often based on self-report. Using validated smart ring data, this study quantifies physical activity (PA) intensity as metabolic equivalents of task (MET) and examines its association with objectively measured sleep disturbance in this population.

This was a 14-day observational study in a long-term care facility using a smart ring. Fifteen participants were enrolled, 11 met eligibility at baseline, and seven completed the exit visit. The Oura Ring measured PA and classified in vigorous, moderate, and light intensities from METs. Sleep disturbance was measured as any 5-min segment with movement measured by the accelerometer during sleep that coincided with changes in heart rate measured by the photoplethysmography sensor and changes in skin temperature measured by the temperature sensor.

Vigorous PA was significantly related to reduced sleep disturbance, with each additional second linked to a 0.18-s decrease in disturbance (B = -0.18, 95% CI [-0.29, -0.07]). Moderate PA had a small, nonsignificant positive coefficient (B = 0.01, p > .05). Light PA showed a significant negative association, describing slightly reduced sleep disturbance with increased time in light PA (B = -0.01, 95% CI [-0.01, -0.01]).

Light and vigorous PA were associated with lower sleep disturbance in older adults with MCI, suggesting that intensity-targeted programs emphasizing light (e.g. walking) and vigorous (e.g. swimming) activity may help reduce sleep disturbance in this population.