EEG Analysis for the Objective Assessment of Drowsiness

OSS is based on the visual analysis of electrophysiological variables (EEG (C4, O2, C3, P3), 1 vertical EOG and 1 horizontal EOG).

Each state of drowsiness (score) corresponds to a specific EEG activity accompanied by well-differentiated blinking and eye movements

The KSS is a self-administered questionnaire that measures, on a 10 point Likert scale ranging from=1 to "fully awake" to 10 ="extremely drowsy". This measure has very good external validity on EEG synchronization measures and on the cognitive and behavioral performance of subject in relation to his or her ability to maintain wakefulness.

This is test ability to stay awake in laboratory conditions conductive to falling asleep. The sleep onset latency is obtained during an electrophysiological test (EEG, EMG and EOG).

On the driving simulator the subjects will drive on a highway scenario representing a reconstruction of the real highway. Number of inappropriate line crossings (ILC) will mesured.

An ILC was recorded when the car crossed a right or left lateral lane marker, whatever the duration and the amplitude of the crossing. Exceptions were overtaking manoeuvres or some other necessary driving action.

On the driving simulator the subjects will drive on a highway scenario representing a reconstruction of the real highway. Standard deviation of the lateral position of the car (SDLP in cm) will mesured.

Lateral Position was defined as being 0 when the car was in the center of the lane, with positive value to the right and negative values to the left.

The reaction time of subject to the presentation of a "target" stimulus (Continuous Performance Test, CPT)

The test examines the ability to concentrate and maintain attention over a long period (30mn) (TAP vigilance test)

Reaction-timed task that measures the consistency with which subjects respond to a visual stimulus.

Questionnaire suggests participant's attention and thoughts were entirely focused on task-related stimuli

The Munich Chorotype Questionnaire (MCTQ) quantifies the chronotype according to the phase of entrainment based on the reported the mid-time of sleep; The MCTQ parameters are mid-sleep on weekdays (MSW in hr), mid-sleep on free days (MSF in hr) and mid-sleep on free days corrected for sleep debt on weekdays (MSFsc in hr). The MSFsc score (used as a chronotype indicator) represents a continuum of circadian preference, with an increasing tendency toward the evening type. MCTQ parameters are represented by hours, ranging from 0 hour (extreme morningness) to 12 hours (extreme eveningness).

The Horne and Ostberg morning/evening questionnaire (MEQ) quantifies the chronotype.

The MEQ contains19 questions on life preferences (activity, sleep-wake cycle, meals) and the state of fatigue and drowsiness at certain times of the day. The MEQ score ranges from 16-86, with evening type ranging from16-41, neither or intermediate type from 42-58, and morning type from 59-86.

To assess participants' general tendency to daydream in daily life

Total sleep time, the number of minutes asleep in bed after "lights off", will be calculated using a polysomnographic recording (PSG). EEG, EOG and EMG will be recorded during sleep.

Sleep onset latency, the minutes from lights off to sleep onset, will be calculated using a polysomnographic recording (PSG). EEG, EOG and EMG will be recorded during sleep.

Sleep efficiency, the ratio of the total time spent asleep (total sleep time) in a night compared to the total amount of time spent in bed, will be calculated using a polysomnographic recording (PSG). EEG, EOG and EMG will be recorded during sleep.

Amount of N1,N2,N3 and R stage (expressed in p% of TST) will be calculated using a polysomnographic recording (PSG). EEG, EOG and EMG will be recorded during sleep.

Wake after sleep onset, number of minutes scored as wake from sleep onset to the last minute scored as sleep while in bed, will be calculated using a polysomnographic recording (PSG). EEG, EOG and EMG will be recorded during sleep.

Total sleep time, the number of minutes asleep in bed after "lights off", will be calculated using an actigraph (wearable sleep test that tracks wrist movements)

Sleep onset latency, the minutes from lights off to sleep onset, will be calculated using an actigraph (wearable sleep test that tracks wrist movements)

Sleep efficiency, the ratio of the total time spent asleep (total sleep time) in a night compared to the total amount of time spent in bed will be calculated using an actigraph (wearable sleep test that tracks wrist movements)

Wake after sleep onset, number of minutes scored as wake from sleep onset to the last minute scored as sleep while in bed will be calculated using an actigraph (wearable sleep test that tracks wrist movements)