Circadian multimodal physiological, ocular and behavioural data from a 40-hour forced-desynchrony protocol

We present a multimodal dataset from twelve healthy adults (aged 19-30 years, 50% female) who completed a 40-hour ultra-short sleep-wake forced desynchrony protocol which scheduled 2 h 30 min of wakefulness in dim light and 1 h 15 min of sleep in darkness (2:1 wake:sleep ratio), with the protocol ending after the last wake period. This schedule compressed the typical 24-hour day into an ultradian 3 h 45 min cycle to decouple circadian and homeostatic influences on physiology and behaviour. During each wake interval, participants completed repeated assessments of visual psychophysics (chromatic temporal contrast sensitivity), pupillometry with silent-substitution stimuli, ocular structure (optical coherence tomography) and physiology (intraocular pressure), psychomotor vigilance, salivary hormones, and standardised questionnaires, alongside continuous actigraphy, electrocardiography, and recordings of core and peripheral temperature, blood pressure, and interstitial glucose. Two supplementary evening sessions under experimental light exposure and dim-light conditions provide comparison data on circadian phase (salivary melatonin concentration, dim-light melatonin onset). Data collected from one pilot participant and screenings of two excluded candidates are additionally included. This dataset supports reuse for investigating circadian dynamics across multiple domains beyond the retinal-function hypotheses of the original study.