Psychiatry Investig.  2017 Nov;14(6):839-843. 10.4306/pi.2017.14.6.839.

Asymmetrical Electroencephalographic Change of Human Brain During Sleep Onset Period

• Park DH
• Shin CJ

• KMID: 2402412
• DOI: http://doi.org/10.4306/pi.2017.14.6.839

Abstract

OBJECTIVE
Human cerebral hemisphere is known to function asymmetrically with daytime left hemisphere superiority in most right-handed persons. It may have relevance to the localization of specific function of the brain. This study attempted to reveal whether the functional cerebral asymmetry in the wakeful state is still maintained throughout the sleep onset period.
METHODS
Thirty-channel EEG was recorded in 61 healthy subjects. The EEG power spectra of each of the seven frequencies were compared between the two kinds of 30-second states; the wakeful stage and the late-sleep stage 1.
RESULTS
The asymmetrical indices of sleep stage 1 at several fronto-central leads were decreased in the delta, theta, alpha-2, and all beta bands. Conversely, at parts of parieto-occipital leads showed an increase in the indices of the theta, alphas, beta-1, and beta-2 bands. Any fronto-central leads did not show an increase in the index, and no parieto-occipital leads showed a decrease.
CONCLUSION
During the sleep onset period, power spectral asymmetry of the brain showed a different pattern from the wakeful stage. This asymmetrical pattern of EEG powers may suggest a reversal of the left hemispheric dominance during sleep.

Keyword

Cerebral asymmetry; Sleep onset period; EEG spectra

MeSH Terms

Brain*
Cerebrum
Electroencephalography
Healthy Volunteers
Humans*
Sleep Stages