Extreme sleepiness: quantification of EOG and spectral EEG parameters

Area of Science:

• Neuroscience
• Sleep Science
• Psychophysiology

Background:

• Previous research indicated correlations between subjective sleepiness and EEG/EOG measures during monotonous work.
• Objective markers for quantifying extreme behavioral sleepiness were not well-established.

Purpose of the Study:

• To establish electroencephalogram (EEG) and electrooculogram (EOG) criteria for identifying extreme behavioral sleepiness.
• To validate EEG and EOG parameters as indicators of sleepiness in active individuals.

Main Methods:

• Utilized Medilog tape-recorders to capture EEG and EOG data during a 45-minute visual vigilance test.
• Performed computerized spectral analysis on EEG data and visual scoring of EOG for slow eye movements (SEM) in 7.5-second epochs.
• Correlated EEG/EOG parameters with performance metrics, including hits, misses, and experimenter-scored dozing off episodes.

Main Results:

• Epochs preceding dozing off showed significantly higher alpha, theta, and delta power density and SEM activity compared to epochs preceding hits.
• Increased power density and SEM activity were observed up to one minute before dozing off events and missed signals.
• Alpha power density peaked in the final three epochs before dozing off, while delta and theta power density further increased.

Conclusions:

• Behavioral sleepiness is systematically reflected in spectral EEG and EOG parameters.
• These findings support the use of EEG and EOG variables to indicate sleepiness in real-life, active situations.
• The homogeneous response patterns across subjects suggest reliable application of these criteria.