Fig. 1

Study design and cortical excitability assessment. a Overview of the whole experimental protocol and the timing of the different steps for a representative subject with bedtime at 11:00PM and wake time at 07:00AM. AN: adaptation night with polysomnography to screen for sleep apnea; BN: baseline night under EEG recording. b Cortical excitability over the frontal cortex was assessed using neuronavigation-based TMS coupled to EEG. Left: reconstructed head with electrodes position; Right: representative location of TMS coil and stimulation hotspot with electric field orientation. c Butterfly plot of TMS-evoked EEG response over the 60 electrodes (−100 ms pre-TMS to 300 ms post-TMS; average of ~250 trials). d Representative TMS-evoked EEG potential (0–32 ms post-TMS) in the five TMS-EEG sessions with indicative clock time and circadian phase (15° = 1 h). Cortical excitability was computed as the slope (µV/ms) of the first component of the TMS-evoked EEG response at the electrode closest to the hotspot (dotted line: example for 10:00AM session).