Sleep dependent autonomic correlates of affect and arousal in younger and older adults

Aging alters affect, with older vs. younger adults exhibiting greater positive and reduced negative affect. Sleep and autonomic factors contribute to this change, yet it is untested whether sleep-dependent autonomic activity plays a role. The current study examined bidirectional associations between affect, arousal, sleep architecture, and cardiac autonomic activity across a daytime nap in healthy younger and older adults.

Polysomnography and electrocardiogram were collected during a midday nap. Sleep architecture and autonomic activity outputs (i.e. high frequency, HF-HRV, and low frequency, LF-HRV, heart rate variability) were extracted. Affect ratings (assessed via the Multiple Affect Adjective Checklist), captured before and after the nap, were considered along two continua: (1) positive and negative valence and (2) low and high arousal. Positivity ratings (positive - negative valence) were determined within the two arousal categories.

Younger adults reported stronger positivity for low- relative to high-arousal affect after the nap, whereas positivity did not differ by arousal in older adults. Wake and NREM autonomic activity was lower in older than younger adults. Higher waking and NREM LF activity were associated with stronger post-nap positivity, whereas higher HF activity was associated with diminished post-nap positivity. Pre-sleep positivity ratings were not meaningfully associated with HRV during sleep. Sleep and wake findings were broadly consistent across age cohorts.

The current study extends previous work linking sleep-related autonomic activity and psychosocial outcomes and offers that autonomic activity during wake and sleep may work synergistically to calibrate affective experiences across the lifespan.