Electroencephalography artifacts in workplace alertness monitoring.
OBJECTIVE
This study assessed the effect of removing artifacts from workplace electroencephalography (EEG) recordings on power spectra and the consequent interpretation of changes in alertness.


METHODS
EEG was recorded for 27 air traffic controllers on the night shifts of four roster cycles. On two of the four night shifts, each controller was given a 40-minute opportunity to nap, while on the other two they remained awake (105 shifts in total). Recordings for the last hour of each night shift were screened for artifacts by an experienced viewer (who viewed the EEG in isolation from other electrophysiological recordings). The effects of the nap opportunity on the EEG power spectra were then analyzed in a mixed model analysis of variance in the presence and absence of artifact-contaminated data.


RESULTS
Overall, 89.3% of the EEG recordings contained artifacts. Removal of these data markedly altered the interpretation of how the nap opportunities affected the EEG power spectra. The spectral parameters of the artifact appeared to be different when the participants were given the opportunity to nap.


CONCLUSIONS
Removal of artifacts can dramatically affect the interpretation of workplace EEG recordings. This potential source of error is often unreported.
Gale
Jesse
J
Sleep/Wake Research Centre, Massey University, 102 Adelaide Road, Newtown, Wellington 6012, New Zealand. jesse.gale@gmail.com
Signal
T Leigh
TL
Garden
Alexander L
AL
Gander
Philippa H
PH
D000328:Adult; D000704:Analysis of Variance; D016477:Artifacts; D001359:Aviation; D001921:Brain / Q000502:physiology*; D003071:Cognition; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic; D009520:New Zealand; D012815:Signal Processing, Computer-Assisted; D012890:Sleep / Q000502:physiology; D014940:Work Schedule Tolerance / Q000502:physiology*; D017132:Workplace