# Daily experiences affect the timing rather than the structure of sleep

## TL;DR

Daily activities mainly affect when people fall asleep, not the overall quality or structure of their sleep.

## Contribution

The study shows that sleep timing is more affected by daily experiences than sleep structure.

## Key findings

- Sleep onset is delayed after more experience-rich or pleasurable days.
- Workdays are associated with longer sleep and deeper sleep stages.
- Social activity increases REM latency, and alcohol reduces sleep onset latency.

## Abstract

Sleep characteristics may be affected by daytime experiences, a fact that can be leveraged by nonpharmacological interventions to improve sleep.

To investigate the effect of daily experiences on sleep in an ecologically valid within-participant design.

We leverage the Budapest Sleep, Traits and Experiences Study, a large multiday observational study (N = 1901 nights in total) with extensive daily diaries and mobile electroencephalogram (EEG) recordings conducted for at least 7 days per participant to investigate how naturally occurring daily experiences such as social activity, emotional involvement, or mental strain affect sleep during the subsequent night.

The strongest influence was on the timing of sleep onset: Even after controlling for day of the week, sleep onset occurred later after more experience-rich days and pleasurable activities (B = 0.05-0.89 hours, Pmax = .002). After statistically accounting for this extended wakefulness, we found limited evidence that daily experiences influence sleep characteristics. Only 4 effects survived correction for multiple comparisons: Sleep (B = 23 minutes, P = .002) and N3 duration (B = 6 minutes, P = .003) were longer after days with time at the workplace, rapid eye movement (REM) latency was increased after social activity (B = 8.6 minutes, P < .001), and sleep onset latency was reduced after alcohol consumption (B = −1.1 minute, P = .004).

Our work shows that, aside from homeostatic effects resulting from extended wakefulness, sleep is relatively resilient to and only affected by a few distinct daytime experiences. Nonpharmacological interventions seeking to change sleep may need to utilize behavioral modifications exceeding normal day-to-day variation.