Las Vegas is a 24-hour city 365 days a year. Casinos, bars, supermarkets, almost all gas stations, even some health clubs and video stores cater to customers at all hours of the day and night (many people work odd hours here).
Most museums and attractions are open seven days a week.
Most pharmacies are open seven days a week. Many, though, including local outposts of Walgreens and CVS pharmacy—several of them on the Las Vegas Strip—offer 24-hour and drive-through services.
Shopping hours vary greatly around town, but many stores are open weekdays and Saturday from 9 or 10 am until 9 or 10 pm and Sunday from 10 or 11 am until 5 or 6 pm. The malls and souvenir shops on the Strip and Downtown often remain open until midnight, and some are open 24 hours. Quite a few grocery stores are open around the clock.