Browsing by Author "Päiviö, Elisa"

Objectives: Mental health problems as well as chronic stress and worries have been shown to have an established connection to sleep quality, but the individual effects of acute, stressful situations encountered in everyday life have received less attention. Rapid eye movement (REM) sleep has a hypothesized role in the processing of emotional memories and may therefore be affected by daytime acute stress. In experimental animal models and non-experimental human studies on healthy subjects acute stress has been associated with increases in REM sleep spectral power in the theta and beta ranges. The aim of this study was to investigate in an experimental setting utilizing virtual reality, whether an acute stress experience influences REM spectral power at these frequency ranges. Methods: Two groups of healthy young adults (N=31, 61 % female, mean age 25.5 years, SD = 3.46) underwent stress inducing or neutral virtual reality scenarios after which they spent the night at a sleep laboratory where their brain activity during sleep was measured with electroencephalography (EEG). To analyse the differences in theta and beta frequency activity during REM sleep, the EEG signal was Fourier transformed to yield power spectral density (PSD) values. Results: Statistical analysis of PSD values revealed that participants in the stress condition exhibited higher REM sleep theta power than controls when controlling for the effects of sex and age. Additionally, sex was found to have a statistically significant effect on REM sleep theta and beta power, with females exhibiting higher power. Age had a negative relationship with spectral power at the theta range, as well as with central low and high beta power. Conclusions: The finding that experimentally manipulated acute stress increases REM sleep theta power during the following night indicates the importance of REM sleep theta activity in the adaptive processing of acute stress, possibly due to the emotional processing of the stressful memory. This study also underlines the importance of sex and age in understanding the relationship between acute stress and REM sleep.