Sleepless in the city: How urban life affects your rest

The price of living in a city that never sleeps is precisely that: inadequate sleep. And we must not forget that proper nighttime rest, while often undervalued, is a key physiological process to maintain good health. If we do not get enough sleep, our well-being will end up paying the consequences. But how much is enough? It depends on age, but a healthy adult, on average, needs seven to nine hours a day, and that figure increases when it comes to children, who may need from nine to even 16 hours of sleep a day.

Now, when should you sleep? Being diurnal animals, we sleep at night. With some variations, however, due to the different chronotypes: some people tend to go to bed and wake up later (the night owls or evening people) while others have a natural tendency to wake up and go to sleep early (the early birds or morning people).

Despite these individual differences, nighttime is the time that our physiology reserves for sleep. Over millions of years, evolution has made our physiological processes revolve around the alternation between light and darkness. However, the night has changed a lot since electric light became widespread a century and a half ago; today, in many urban environments, “night” and “darkness” have stopped being synonymous. Artificial light has allowed human beings, whose eyes are made for daylight, to colonize the night, destroying its darkness and extending their period of activity to all kinds of late hours.

The light that keeps us awake

Artificial light at night is considered a pollutant and leads to a series of health problems. First of all, it keeps us awake for longer. Studies indicate that as the level of artificial light in the nighttime environment increases, adults and the elderly tend to sleep less. It has also been observed that artificial light at night, both outdoors and indoors, can increase sleep problems by 22%. This light is the enemy of sleep because it disorients the clock that regulates it: it tells it that it is daytime, not yet time to sleep.

In addition to reducing sleep hours (something already serious), excessive use of artificial light at night can have other serious health consequences. Among them, a greater probability of suffering from cardiovascular and metabolic disorders (obesity or diabetes), mental health disorders and even some types of cancer such as breast, prostate or colorectal, has been described. Controlled laboratory studies leave no doubt about the harmful effects of artificial light at night.

However, in epidemiological terms, the disparity in results is still a cause of controversy. This is due, above all, to the so-called confounding factors: circumstances specific to the most illuminated areas that prevent the experts from differentiating which damages are due to night light and which are due to other factors.

Traffic and nightlife noise, the enemy of health

One of those confounding factors is noise. With humans able to colonize the darkness thanks to the electric light , nights have become noisy, depriving us of the quiet we need to fall and stay asleep. The noise that sneaks into our home harms us at any time of the day, whether it bothers us or not; but at night, it also interferes with our sleep.

According to the European Environment Agency, prolonged exposure to environmental noise contributes to 48,000 new cases of heart disease and 12,000 premature deaths each year in Europe. In addition, 22 million people suffer from chronic discomfort and 6.5 million suffer from major chronic sleep disorders. It is estimated that one million years of healthy life are lost each year due to the effects of noise, including ischemic heart disease and sleep disorders, which account for most of the noise-related disease burden.

The negative consequences of road traffic noise have been widely demonstrated. However, the cities have other sources of noise that cause discomfort at night. One of the most important is nightlife. Another one is street cleaning, which often takes place at night until the early morning. Paradoxically, we could say that cleaning the streets at night interferes with the cleaning that sleep sets in motion in our brain through the glymphatic system.

What can local governments do to protect our rest?

Many of the problems that make it difficult to sleep could be solved with greater awareness and empathy on the part of citizens. However, an adequate legal framework is also necessary, and the authorities need to effectively ensure compliance.

How could a local government help its citizens sleep better? To begin with, we must start from the premise that sleep, due to its close connection with health, should always be prioritized over other things like leisure. Therefore, some suggestions would be:

· Limiting the hours of use of noisy street cleaning machinery. Even if the vehicle’s engine is electric and silent, the water pumps are not. This should never be done at night.

· Replacing noisy public transport vehicles with electric models and ensuring that private vehicles comply with regulations.

· Reducing the hours and the number of tables used by the hospitality industry in residential areas.

· Lowering the permitted volume in noisy establishments (which can often be harmful to the clients’ hearing) and avoiding nighttime operation in residential areas, not only due to the structural transmission of noise, but also due to the frequent accumulation of people outside.

· Not having noisy shows in areas close to inhabited homes, especially at night.

· Reviewing the location of streetlights and other sources of light to reduce light pollution in general and, especially, that which enters homes through windows.

And finally, the most important thing: understanding, both at the institutional and the individual level, that to build a healthier society it is essential to protect an environment that facilitates our sleep and that of our neighbors.

Sleep and let sleep.

María Ángeles Bonmatí is a postdoctoral researcher at the Spanish Network for Biomedical Research in Fragility and Healthy Aging (CIBERFES) and a collaborating professor at the University of Murcia. This article originally appeared in Spanish in The Conversation.