Evidence for age-associated disinhibition of the wake drive provided by scoring principal components of the resting EEG spectrum in sleep-provoking conditions

ABSTRACT

Age-associated changes in different bandwidths of the human electroencephalographic (EEG) spectrum are well documented, but their functional significance is poorly understood. This spectrum seems to represent summation of simultaneous influences of several sleep–wake regulatory processes. Scoring of its orthogonal (uncorrelated) principal components can help in separation of the brain signatures of these processes. In particular, the opposite age-associated changes were documented for scores on the two largest (1st and 2nd) principal components of the sleep EEG spectrum. A decrease of the first score and an increase of the second score can reflect, respectively, the weakening of the sleep drive and disinhibition of the opposing wake drive with age. In order to support the suggestion of age-associated disinhibition of the wake drive from the antagonistic influence of the sleep drive, we analyzed principal component scores of the resting EEG spectra obtained in sleep deprivation experiments with 81 healthy young adults aged between 19 and 26 and 40 healthy older adults aged between 45 and 66 years. At the second day of the sleep deprivation experiments, frontal scores on the 1st principal component of the EEG spectrum demonstrated an age-associated reduction of response to eyes closed relaxation. Scores on the 2nd principal component were either initially increased during wakefulness or less responsive to such sleep-provoking conditions (frontal and occipital scores, respectively). These results are in line with the suggestion of disinhibition of the wake drive with age. They provide an explanation of why older adults are less vulnerable to sleep deprivation than young adults.

KEYWORDS:

• Aging
• EEG
• principal component analysis
• sleep and wake promoting processes
• sleep-wake regulation
• sleep debt
• sleepiness
• sleep pressure

Acknowledgments

We would like to thank Dr. Evgeniy G. Verevkin for his help in analysis of some of the waking EEG recordings.

Declaration of interest

The authors have declared that no competing interests exist.

Funding

The experimental studies were supported by the Russian Foundation for Basic Research (grants 07-06-00263-а, 10-06-00114-а, 13-06-00042-a, and 16-06-00235-a) and the Russian Foundation for Humanities (grants 06-06-00375-a, 12-06-18001-e, and 15-06-10403-a).