Are There Levels of Consciousness?

Trends Cogn Sci. 2016 Jun;20(6):405-413. doi: 10.1016/j.tics.2016.03.009. Epub 2016 Apr 18.


The notion of a level of consciousness is a key construct in the science of consciousness. Not only is the term employed to describe the global states of consciousness that are associated with post-comatose disorders, epileptic absence seizures, anaesthesia, and sleep, it plays an increasingly influential role in theoretical and methodological contexts. However, it is far from clear what precisely a level of consciousness is supposed to be. This paper argues that the levels-based framework for conceptualizing global states of consciousness is untenable and develops in its place a multidimensional account of global states.

Keywords: anaesthesia; disorders of consciousness; global state of consciousness; levels of consciousness; sedation; sleep.

Publication types

  • Review

MeSH terms

  • Brain / physiology*
  • Consciousness / physiology*
  • Electroencephalography / methods*
  • Humans
  • Sleep / physiology*