Christopher Hamilton’s Living Philosophy: Reflections on Life, Meaning and Morality (2001) … “includes a fascinating essay entitled ‘The Need to Sleep’, where he notes that philosophers have not paid sufficient attention to this extraordinary phenomenon. Well, a decade on, this is the beginning of a response to Christopher’s wake-up call.”
Since all animals sleep, we assume it has a biological purpose. The trouble is, we don’t know what that purpose is. There are many theories – energy conservation, growth promotion, immobilisation during hours of darkness when it might be dangerous to be out and about, consolidation of memories – but they are all open to serious objections. William Dement, one of the leading researchers of the last century and co-discoverer of Rapid Eye Movement sleep, concluded from his fifty years in the forefront of the field that “the only reason we need to sleep that is really, really solid, is that we get sleepy.”
It is easy to see why philosophers have, on the whole, avoided talking about sleep. Those who see the aim of philosophy as being to cultivate the most unpeeled mode of wakefulness are likely to treat sleep as an enemy.
Dreams, of course, have figured more significantly in philosophy. Being a mode of consciousness – prompting Aristotle to say that “the soul makes assertions in sleep” (On Dreams 458b) – dreams seem one step up from the mere putting out of zzzs.
Most of us spend a third of our lives asleep, so perhaps we need to think a bit more about it.