You could stay up all night in Paris or New York – but London’s licensing laws ensured that most pubs shut at 11pm, and the Tube stopped running soon after.

But London is changing, with more liberal licensing laws, an impressive night bus service, and fewer restrictions on night-time deliveries to make more efficient use of jammed roads. Boris Johnson successfully negotiated with the unions to bring in the Night Tube and Sadiq Khan has appointed London’s first Night Czar, the suitably named Amy Lamé. Digital technology is changing us from diurnal to nocturnal animals, making it easier to meet up, travel, or conjure up entertainment through the night.

This edition of London Essays looks at a new and fast-developing agenda in urban policy: the city after dark. We have deliberately avoided being too uncritical in our approach, recognising that the move to a 24/7 city has costs as well as benefits; and we have also sought to shine light on neglected or unexpected aspects of London at night.

Much discussion of the night-time city understandably revolves around late-night entertainment. Jo Negrini, a member of the Mayor’s Night Time Commission, highlights the regulatory threat to clubs and music venues following the closure of Fabric, which left many of those involved in nightlife feeling bruised. She suggests ways for local and city government to create conditions for nightlife to thrive. Alex Proud argues that late-night entertainment needs room to get down and dirty, to harness the energy of chaos and displacement. And Mirik Milan, the Night Mayor of Amsterdam, offers some advice to his new London counterpart, describing some of the practical steps that Amsterdam has taken in the process of developing a nightlife that is internationally renowned.

But there is more to the night-time economy than merely having fun, as Caroline Artis points out. London’s status as a global city means that more and more of us are staying up late or getting up early to connect to colleagues and clients in different time zones. As some of us sleep, others are up readying the city for the next day: cleaning offices, delivering goods, prepping food. Research suggests that shift work can take a heavy toll on our health and wellbeing, raising concerns about whether London’s growing army of night workers is being adequately protected. A night living wage, anyone?

Night and day are the rhythms of our planet and of being human; not everything about our times of wakefulness and rest can be measured in narrow economic terms. Much of the surprising amount of wildlife with which we share our city depends on long periods of darkness.

Mathew Frith writes about the pressures on London’s animals from the night-time economy, noting, for example, that more night traffic will probably be very bad news for London’s endangered hedgehog population, while light pollution can disrupt the foraging patterns of bats. Frith’s warnings about light pollution are picked up by Robert Massey in an essay on stargazing. London is 91 per cent light saturated, making it a frustrating place to live for the city’s many amateur and professional astronomers. Patricia Brown argues that we should think more creatively about lighting, citing Lyon’s imaginative integration of lighting design into urban planning and its use of light alternately to exhilarate and quieten the city.

The Illuminated River project, which will light up 17 Thames bridges, marks a big step forward for London. It would be good to see the capital building on this and putting lighting at the centre of its cultural, design and public realm strategy.

For most of history, night in the city has been a murky time of suspicion and primitive fears. Matt Lloyd-Rose suggests these visceral anxieties still dog our attitude to gangs on the night-time streets. Ben Judah reports from underpasses and doorways on the large number of migrant Londoners sleeping rough. Christina Patterson reflects on being a woman on the Night Tube and on early-morning buses. And Ian Jack offers a personal take on the rhythms, sound and moods of night-time London from his bed. Pillow writing.

The new Night Czar will have her work cut out for her. No doubt she will want to concentrate on supporting London’s nightlife. But her remit should go wider. London, once so sleepy, is now open 24 hours and we need to think around the clock.