Novel brain biomarkers of performance impairment in good sleepers

50 healthy individuals will be recruited to undergo an experimental laboratory protocol following a screening visit and after obtaining informed consent. One week of actigraphy and sleep-wake diary and indoor-outdoor activity logs, will be performed prior to the test visit to measure sleep hours and activities at home, and participants will be advised to observe regular sleep hours with 8-hours in bed. The experimental protocol visit consists: - baseline sleep study followed by 28 hours of extended wakefulness challenge (EWC) with detailed assessment including: Primary performance outcomes measure -Three 90 minute computerised AusEd driving simulator tasks measured at Time 1 (9.30am, 3.5 hours awake), Time 2 (2.30am, 20.5 hours awake) and Time 3 (8.30am, 26.5 hours awake) Secondary performance outcome measure -10 minute psychomotor vigilance test (PVT) measures every 2 hours throughout the EWC starting from midday. Primary Predictor Variables -Baseline sleep study is performed from 10pm-6am (EEG data will be subjected to spectral power analysis as part of data processing/analysis) -Auditory Event Related potentials (ERP) data will be collected at between 8.30-9.30am (baseline assessment only) -Resting awake EEG during a 7 minute Karolinska Drowsiness Test measure every 2 hours throughout the EWC startinf at midday -Magnetic Resonance Spectroscopy/Diffusion Tensor Imaging occurs within 1 week prior to laboratory EWC visit (assessed at baseline only) Secondary Predictor Variables -mRNA expression profiles from baseline to end of EWC (blood/mRNA samples collected at 6.15am upon awakening and 6.15am the following morning after 24hours of wakefulness -Posture/Balance control assessments measured every 2 hours throughout the EWC starting at midday -Peripheral Blood Pressure measures every 2 hours throughout the EWC starting at midday Computerised performance tests measure every 2 hours through out the EWC starting at midday : - Working memory (N-back 1,2,3) - Visuomotor skills (Digit Symbol Substitution Task) - 4 Choice Reaction Time Task - Letter Cancellation Task - Emotion Perception Task - Thermal sensation scale - Central Blood Pressure and Pulse Wave Analysis (PWA) measures every 2 hours throughout the EWC starting at midday - Statistical Learning Task measured at baseline (8.30pm prior to baseline sleep study) and at 8.30pm 24 hours later. - Actigraphy variables (actigraphy data collected 1 week prior to EWC) - PSG sleep study variables (collected during the baseline sleep study just prior to EWC) - Genetic polymorphisms (genetic analysis from blood samples collected at start and end of EWC will occur at the completion of the study) - Inflammatory marker profiles (from blood sample analysis collected at start and end of EWC will occur at the completion of the study) - Brief Smell Identification Test (B-SIT) is collected at baseline only at 7.30pm prior to baseline sleep study - State anxiety questionnaire administered every 2 hours throughout the EWC starting at midday - Karolinska Sleepiness Scale administered every 2 hours throughout the EWC starting at midday