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Consciousness with open eyes
Sleep does not switch consciousness off: it transforms it. At the wheel, instead, it splits it - and part of you is already elsewhere.
Last revision: 26.09.2026
| 26.09.2026 | Text and sources revised: scientific and language clarifications. |
Common sense says: awake equals conscious, asleep equals switched off. Research disproves it. The dream is proof that an intense experience, sometimes more vivid than waking, can happen while we are disconnected from the world. Consciousness has no switch: it changes shape. And not always downward.
On the threshold it can take unexpected forms. In a lucid dream attention reignites inside sleep; in yoga nidra dopamine release rises and the state of consciousness shifts, it does not switch off. Waking is one of its forms, not the only one.
How it changes can be measured. Massimini and Tononi, with a brief magnetic pulse and EEG, showed that the same stimulus produces a rich, widespread response in waking and in dreaming, and only a simple, local wave in deep dreamless sleep. Hence the Perturbational Complexity Index: high in waking and dreaming, low in deep sleep. Not a switch, but a slider that rises and falls (Casali and colleagues, 2013). For Giulio Tononi's integrated information theory, the signature of consciousness is how much united and differentiated activity the brain can hold at once.
सुषुप्ति
Sanskrit · suṣupti
Deep dreamless sleep. For the Indian tradition not a void but a full state: the very question science still asks.
And the road? Here the story is different. Recordings inside the brain show that sleep can be local: some areas sleep while others stay awake (in rats, in the laboratory: Vyazovskiy and colleagues, 2011; similar signs in humans in Nir and colleagues, 2017). At the wheel it is the most insidious risk, because consciousness does not fall uniformly: it splits. One part keeps driving, another has already slipped into sleep. Microsleeps are pieces of sleep inside waking, visible on EEG (in patients, in the laboratory: Hertig-Godeschalk and colleagues, 2020), and according to a solid hypothesis local sleep is one of the mechanisms behind them and behind attention lapses.
Sleepiness at the wheel, then, is not a light dimming: it is a threshold crossed while underestimating how close it is, while part of you stays at the wheel and another is already across. The signal comes first: the drivers who fell asleep had felt their sleepiness growing for a long time (Reyner and Horne, 1998, in a simulator).
Consciousness does not switch off: it shifts. At the wheel the signal is there: the danger is not taking it seriously.
So listen to it early: when part of you is already across the threshold, it is no longer that part that can tell.
Sources
Casali AG et al. A theoretically based index of consciousness independent of sensory processing and behavior. Science Translational Medicine 5:198ra105, 2013. DOI 10.1126/scitranslmed.3006294.
Vyazovskiy VV et al. Local sleep in awake rats. Nature 472:443-447, 2011. DOI 10.1038/nature10009.
Nir Y et al. Selective neuronal lapses precede human cognitive lapses following sleep deprivation. Nature Medicine 23:1474-1480, 2017. DOI 10.1038/nm.4433.
Hertig-Godeschalk A et al. Microsleep episodes in the borderland between wakefulness and sleep. Sleep 43(1):zsz163, 2020. DOI 10.1093/sleep/zsz163.
Reyner LA, Horne JA. Falling asleep whilst driving: are drivers aware of prior sleepiness? International Journal of Legal Medicine 111(3):120-123, 1998. DOI 10.1007/s004140050131.
Tononi G. An information integration theory of consciousness. BMC Neuroscience 5:42, 2004. DOI 10.1186/1471-2202-5-42.