What does your ideal bedtime routine involve? A nice cup of cocoa or a glass of wine? Curling up with a good book? Some intense flossing, a relaxing bath or a vigorous bout of intercourse? Whatever its exact ingredients, we all tend to have particular regimes with which we aspire to start and end the day. And so, of course, do cultures as a whole. Historians of 20th-century Britain have doubtless already turned their attention to the decline of separate bedrooms, the invasion of the duvet, the disappearance of the nightcap and the rise of jet lag. How we sleep, individually and collectively, says a lot about us.

In medieval and early modern England, it was usually presumed that the key to a good sleep was a happy tummy. Hippocrates, Galen and Aristotle had taught that slumber was chiefly related to digestive processes and the regulation of the body’s humours. Through sleeping, a popular Tudor guide explained, ‘digestion is made better … the body fatter, the mynde more quiete and clere, the humours temperate’. The best way to position yourself at night was to keep your head elevated, ‘well bolstered up’, and to lie first on your right side, and then, halfway through the night, to turn onto your left – never resting on the stomach or on the back (unless you’d just given birth). It was important to wear a nightcap to regulate the temperature of the brain. You might also have tied a pillow around your waist or used a small dog to keep your belly suitably warm. The amount of sleep one needed, doctors thought, was likewise connected to digestion. Healthy people could manage on six to eight hours per night, but those with ‘weake stomakes’ should aim for more.

Fervent Christians, on the other hand, were wont to see excessive sleep as sinful and sleep that had been disturbed as a sign of divine displeasure. Whereas ordinary people needed six hours a night, the Presbyterian Richard Baxter wrote, divinely favoured persons required only five. When overcome by daytime drowsiness himself, he worried that it betokened ‘a sensual unsanctified state of soul’; true Christian discipline was supposed to suppress such bodily weakness. The 18th-century Methodists took the same view. John Wesley rose at four o’clock every morning. Too much sleep was, in his view, ‘the chief, real, though unsuspected cause of all nervous diseases’. (The origins of the famously frugal sleeping habits of Margaret Thatcher, who was a Methodist lay preacher before she became a politician, are easy to discern.) God himself, of course, never dozed off at all. This meant that even children in devout households felt guilty about wasting time when they had a lie-in. In the 17th century the teenage Elizabeth Livingston worried endlessly, in prose and poetry, about her ‘lasynesse’ in ‘staying in bed until noon’: ‘The early lark wellcomes the breake of day,/But I (alass) drouse many hour’s away.’

Over time, though, there were some significant changes. By the middle of the 18th century, leading medical texts, jettisoning centuries of humoral theory, ignored digestion as an explanation of the causes of sleeping and waking, preferring to highlight the newly fashionable neurological foundations of such behaviour. Instead of the stomach, they focused on the brain: it was the mind and the nervous system that were now seen as key to the character and quality of human slumber.

The rise of the cult of sensibility in the 18th century likewise triggered an unprecedented re-evaluation of sleepwalking, sleep deprivation and other kinds of nocturnal disorder. Instead of seeing these as indicators of divine displeasure or supernatural possession, or as a separate, irrational mental state, Romantic artists, poets and philosophers increasingly treated them as positive signs of acute personal sensitivity. In the 1690s, John Locke had firmly maintained that one’s thoughts while sleeping were ‘a very useless sort of thinking’ and irrelevant to one’s real mental outlook: ‘Socrates asleep and Socrates awake, is not the same Person; but … two Persons’. A hundred years later, however, artists such as Shelley (a lifelong sleepwalker), Byron, Blake, Fuseli, Hazlitt, Keats, Coleridge and Wordsworth came to the opposite conclusion: it was the semiconscious or unconscious mind that was the most creative force of all.

Sasha Handley’s new book deftly charts these and other features of how people in 17th- and 18th-century England experienced sleep. She examines sleep as an ideal, a practice and a symbol. Her aim is to give us a sense of the changing nature of sleep in an age when, as such historians as A Roger Ekirch and Craig Koslofsky have recently established, new technologies and ways of urban living were transforming people’s expectations of night-time behaviour.

It’s a great subject, though Handley tends to overplay its importance and, at the same time, to conceive of it somewhat narrowly. We might forgive her for boasting that ‘no other daily activity … consumed as much time, money, and labour as did sleep’ – though what counts as ‘labour’ and ‘activity’? But it is surely going too far to conclude that ‘sleep’s successful pursuit dominated the lives of early modern people’. On the other hand, it’s disappointing that she devotes only a few pages to the common practice of unromantic bed-sharing by people of the same sex, that she mentions ghosts and poltergeists only once (despite having written an entire previous book on 18th-century ghost stories) and that she says nothing at all about sex (which was surely a regular prelude or interruption to slumber). This is an account shaped firmly by a particular set of sources, mainly printed literature and surviving material evidence.

The experience of ordinary, normal sleep was rarely recorded verbally; written accounts tended to be triggered by nocturnal disturbances or problems. Partly for this reason, Handley devotes much space to lovingly re-creating its physical trappings. There are some wonderful descriptions and images of sheets, quilts, night garments, bedchambers, bedsteads and sleeping accessories, among them Charles I’s monogrammed skullcap, linen winding sheets, coral amulets, wickerwork cradles, ceilings decorated with ‘candle marks’ and the lugubrious decor with which, in the 1710s, the widow Elizabeth Dugdale surrounded herself in her sleeping chamber (including ‘three pictures of Death in black frames’). The growing 18th-century fashion for nocturnal socialising led to an increasing acceptance of daytime napping, to which we owe the rise of domestic sofas, daybeds and easy chairs.

By looking at household inventories, she is also able to chart some important changes in where people slept. This was not yet an age in which the term ‘bedroom’ was used in its current sense. Indeed, before the late 17th century, it was common even in larger houses for beds to be located in halls, kitchens, parlours and other public rooms. Yet by 1760 this had become uncommon; for those who could afford it, separate bedchambers were increasingly located on the upper floor of a house.

The book is equally rich in its description of religious views and the trappings of what Handley calls ‘sleep-piety’ among the devout. She perhaps exaggerates the extent to which sleep in early modern culture was associated with ‘vulnerability’, ‘anxiety’ and death. All the same, it is marvellous to learn that Charles II used medicine made from powdered human skulls to help him sleep. If you want to be entertained and instructed as you prepare to slip out of consciousness yourself, do take this book to bed.