Temporal relationships between sleep and physical activity among breast cancer patients with insomnia.

OBJECTIVE

The present study prospectively investigated the day-to-day bidirectional relationships between objective measures of sleep parameters and physical activity among breast cancer patients with insomnia symptoms.

METHOD

A subgroup of participants (N = 66) enrolled in a randomized controlled trial for insomnia comorbid with cancer wore an actigraphic recorder for seven 24-hr periods before the intervention. Multilevel models examined whether sleep parameters (sleep onset latency, wake after sleep onset [WASO], total wake time [TWT], sleep efficiency [SE], and total sleep time [TST]) on a given night predicted the levels of physical activity (daily activity counts and minutes of moderate to vigorous physical activity [MVPA]) the following day and vice versa.

RESULTS

Adjusted models revealed that a lower WASO (β= -.12, SE = .07, p < .05), TWT (β = -.14, SE = .05, p < .05), and TST (β = -.14, SE = .06, p < .05) were significantly associated with a greater daily activity count fluctuation the next day. Conversely, greater total daily count fluctuations were significantly associated with a higher WASO (β = .18, SE = .08, p < .05), TWT (β = .12, SE = .04, p < .05), and TST (β = .22, SE = .08, p < .05) the following night.

CONCLUSIONS

These findings support a reciprocal and complex relationship between sleep parameters and physical activity. While they do not confirm a possible beneficial effect of physical activity on objective sleep parameters, they suggest that successful insomnia treatment could increase daily physical activity in patients with cancer. (PsycINFO Database Record