title: Estimating brain load from the EEG.
abstract: Modern work requires cognitively demanding multitasking and the need for sustained vigilance, which may result in work-related stress and may increase the possibility of human error. Objective methods for estimating cognitive overload and mental fatigue of the brain on-line, during work performance, are needed. We present a two-channel electroencephalography (EEG)-based index, theta Fz/alpha Pz ratio, potentially implementable into a compact wearable device. The index reacts to both acute external and cumulative internal load. The index increased with the number of tasks to be performed concurrently (p = 0.004) and with increased time awake, both after normal sleep (p = 0.002) and sleep restriction (p = 0.004). Moreover, the increase of the index was more pronounced in the afternoon after sleep restriction (p = 0.006). As a measure of brain state and its dynamics, the index can be considered equivalent to the heartbeat, an indicator of the cardiovascular state, thus inspiring the name "brainbeat".
authors.affiliation: Brain Work Research Centre, Finnish Institute of Occupational Health, Helsinki, Finland. anu.holm@ttl.fi
authors.forename: Anu
authors.initials: A
authors.lastname: Holm
authors.forename: Kristian
authors.initials: K
authors.lastname: Lukander
authors.forename: Jussi
authors.initials: J
authors.lastname: Korpela
authors.forename: Mikael
authors.initials: M
authors.lastname: Sallinen
authors.forename: Kiti M I
authors.initials: KM
authors.lastname: Müller
mesh_terms: D000704:Analysis of Variance; D001921:Brain / Q000502:physiology* / Q000503:physiopathology; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology; D006801:Humans; D008297:Male; D011597:Psychomotor Performance / Q000502:physiology; D011930:Reaction Time; D012890:Sleep / Q000502:physiology; D012892:Sleep Deprivation / Q000503:physiopathology; D013647:Task Performance and Analysis; D016526:Workload; D055815:Young Adult