New York City is often referred to as “the city that never sleeps” due to its vibrant, 24-hour activity. This nickname reflects the city’s relentless energy, with businesses, entertainment, and transportation operating around the clock. The 24/7 subway system and numerous late-night venues contribute to its reputation as a place of non-stop action and excitement.

In many “24-hour” cities, plenty of eateries are open until 3 am, some clubs are open until 6 am,^[4] and bars close at 2 am^[5] or a few hours later.

Due to the COVID-19 pandemic, many 24-hour and late-night establishments began closing earlier. Coffee shops in lower Manhattan, in particular, began to close at 9:30 pm, whereas before the pandemic they had frequently closed at 12:30 am.^[36]

The people who make use of these facilities, studies have found, are nevertheless affected by sunrise and sunset.^[37][38] In other words: “that most humans aren’t as influenced by Earth’s light-dark cycle as we used to be” is not fully supported; there is an observed annual shift for “a stretch of three or four months” and “then, the process reversed direction

Los Angeles,^[a] often referred to by its initials L.A., is the commercial, financial, and cultural center of Southern California. With an estimated 3,820,914 residents within the city limits as of 2023,^[8] it is the most populous city in the U.S. state of California and the second-most populous in the United States, behind only New York City. Los Angeles has an ethnically and culturally diverse population, and is the principal city of a metropolitan area of 12.9 million people (2024). Greater Los Angeles, a combined statistical area that includes the Los Angeles and Riverside–San Bernardino metropolitan areas, is a sprawling metropolis of over 18.5 million residents.

The majority of the city proper lies in a basin in Southern California adjacent to the Pacific Ocean in the west and extending partly through the Santa Monica Mountains and north into the San Fernando Valley, with the city bordering the San Gabriel Valley to its east. It covers about 469 square miles (1,210 km²),^[6] and is the county seat and most populated city of Los Angeles County, which is the most populous county in the United States with an estimated 9.86 million residents as of 2022.^[17] It is the third-most visited city in the U.S. with over 2.7 million visitors as of 2023