The idea of cities that never sleep seems inseparable with flashing modernity. The constant illumination brought about by electric lighting leads us to imagine that prior to industrialisation, the night was a time of total stagnation; quiet until sunrise.
In fact, prior to mass-electrification, the night was a time of considerable activity, with people generally sleeping in two distinct chunks between nightfall and dawn. In the middle of these two, roughly four-hour-long blocks of sleep, people would get up to all sorts, from visiting neighbours to household chores, from smoking to praying, for about two hours, usually between 1am and 3am, and then return to bed for what was known in English as ‘the second sleep,’ or often ‘the dead sleep’ or ‘the morning sleep.’
Clues indicating this was the norm are littered across a variety of sources. For instance, a sixteenth-century French physician, Laurent Joubert, advises couples looking to conceive to have sex between the first and second sleep as they ‘have more enjoyment’ and ‘do it better.’ Medical references to this period of night-time activity are not usually so exciting; another doctor of the era advised their patients to sleep on their right side during the ‘the fyrste sleep’ and then ‘… turne on the lefte side for this change doth greatly ease the body.’ Another suggested students ought to literally burn the midnight oil between sleeps so that they might be at least ‘in some measure refreshed’ – by their studies, one assumes. Off-the-cuff references to a first and second sleep crop up across literary works, from Dickens’ Barnaby Rudge and Bleak House, to the Odyssey and Chaucer’s The Summoner’s Tale. Writing to Johann Choler Dutch philosopher Erasmus explains that he translated Classical tragedies ‘sometimes in bed, while waiting for the second sleep.’ A number of court documents, diaries, letters and prayer manuals also contain references to first and second sleeps, and the period of activity between them. Historian Roger Ekirch, author of At Day’s Close: Night in Times Past, notes that not only the frequency and variety of the references to first and second sleeps shows it to be standard practice, but also cites the blasé way authors mention what is now a fairly foreign idea writing: ‘It’s not just the number of references – it is the way they refer to it, as if it was common knowledge.’
Ekrich emphasises that although there may be some variances across societies and time periods, the idea of uninterrupted sleep is a relatively modern phenomenon, one which emerged amongst the upper-classes of northern Europe in the late seventeenth-century. From this period onwards, references to first and second sleeps gradually disappeared. Paradoxically, Ekrich attributes this to an increase in more vigorous night-time activity facilitated by street lighting, improved lighting in homes, and the increasing prevalence of late-opening coffee shops in towns and cities. As people retired to bed later, and as a consequence got up later, they increasingly found themselves sleeping through the night, until rising in the middle of the night largely fell out of practice, and eventually our collective memory.
Despite this, scientific findings show that a short spurt of nocturnal activity is likely to still be the default setting of humans’ circadian rhythm, a rhythm continually overridden by our artificial sixteen-hour long photoperiod; that is, the length of time we are exposed to light. In the early 1990s, chronobiologist Thomas Wehr exposed seven subjects to ten hours of light and fourteen hours of darkness — which roughly resembles the amount of light Londoners or New Yorkers would naturally receive in the late autumn. Within four weeks, all of the subjects’ sleep patterns mirrored that of their pre-industrial ancestors: fours asleep, two or so hours awake, and then four more hours asleep. It makes sense. Human beings are the only animals who sleep in a consecutive stint, and many communities living without electrification still practice this kind of staggered sleep, for instance, the Tiv people living largely in rural Nigeria. The phrases ‘first sleep’ and ‘second sleep’ are used in their language to articulate periods of the night in the same way English splits the day into morning and afternoon.
Perhaps what’s most intriguing is the hormonal balance of the subjects during this period of nocturnal activity. While the idea of lying awake in the dark sets off feelings of dread in most modern insomniacs, Wehr’s subjects had remarkably low cortisol levels – to the extent that he referred to this period of wakefulness as an ‘altered state of consciousness not unlike meditation.’
There aren’t huge calls from the medical world – or any other quarter – to return to a biphasic sleep pattern, but this considerable shift in a fundamental part of humanity’s daily routine is yet another clear division between our lives today and the way humans have lived for the vast majority of their history. Insomnia can be lonely, but those who find themselves looking up at their ceiling or quietly creeping about their homes in the dark are in very good company.