Vigilance stages and performance in OSAS patients in a monotonous reaction time task.
OBJECTIVE
To develop improved methods for objective assessment of daytime vigilance. This is important in the diagnosis and therapy control of sleep disorders associated with excessive daytime sleepiness (EDS).


METHODS
Twenty-one patients with EDS due to obstructive sleep apnea were recorded during a daytime 90 min reaction time (RT) test in a monotonous situation. Two EEG, two EOG and a submental EMG channel were recorded simultaneously. The recordings were divided into short, stationary segments of variable length (0.5-2 s) and classified into 7 stages using our previously described system, which includes additional stages for drowsiness.


RESULTS
The duration of RT was linearly correlated to the vigilance state (P<0.05). The appearance of slow eye movements (SEM) was more consistently related to performance impairment than EEG changes.


CONCLUSIONS
Our system can provide a better tracking of vigilance changes than the standardized sleep stage scoring. A 1-2 h test is useful in the assessment of the performance of a subject suffering from EDS. We found that SEMs indicate more sensitive and consistent EDS-related performance impairment than changes in EEG activity.
Kinnari
K
K
Department of Clinical Neurophysiology, Tampere University Hospital, Fin-33521, Tampere, Finland.
Peter
J H
JH
Pietarinen
A
A
Groete
L
L
Penzel
T
T
Värri
A
A
Laippala
P
P
Saastamoinen
A
A
Cassel
W
W
Hasan
J
J
D000328:Adult; D000368:Aged; D001143:Arousal / Q000502:physiology*; D015992:Body Mass Index; D002755:Choice Behavior; D004569:Electroencephalography; D004576:Electromyography; D004585:Electrooculography; D005133:Eye Movements / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D011597:Psychomotor Performance / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology*; D012891:Sleep Apnea Syndromes / Q000503:physiopathology*