Caffeine induces age-dependent increases in brain complexity and criticality during sleep

Area of Science:

• Neuroscience
• Psychopharmacology
• Computational Neuroscience

Background:

• Caffeine is the world's most consumed psychoactive stimulant.
• Understanding caffeine's impact on brain activity during sleep remains incomplete.
• Existing research highlights gaps in knowledge regarding caffeine's neural effects, especially during sleep stages.

Purpose of the Study:

• To investigate the effects of caffeine on brain dynamics during sleep.
• To analyze electroencephalography (EEG) data to quantify caffeine's impact on neural complexity and temporal correlations.
• To explore age-related differences in caffeine's effects on sleep brain activity.

Main Methods:

• Utilized electroencephalography (EEG) to record brain activity in 40 participants.
• Administered a 200 mg dose of caffeine or a placebo.
• Applied inferential statistics and machine learning techniques to analyze sleep EEG data.

Main Results:

• Caffeine ingestion increased brain complexity and flattened the power spectrum's 1/f-like slope.
• Reduced long-range temporal correlations were observed following caffeine intake.
• These effects were most prominent during non-rapid eye movement (NREM) sleep and showed age-dependent differences in rapid eye movement (REM) sleep.

Conclusions:

• Caffeine shifts brain dynamics towards a critical regime, characterized by increased neural excitation and diverse neural activity, particularly during NREM sleep.
• The findings suggest caffeine promotes a state closer to criticality in brain function.
• Age influences caffeine's effects on brain dynamics during REM sleep, but not NREM sleep.