Read the 2:30 a.m. email Elon Musk sent to staff, his first, announcing the end of remote working at Twitter

• Elon Musk has put an end to remote working at Twitter.
• Musk emailed staff to tell them to return to the office for at least 40 hours a week.

Elon Musk has announced the end of remote working at Twitter.

Musk, who took over Twitter on October 27, sent an email to his employees Wednesday for the first time. The email was sent at 2:39 a.m. ET, according to a time stamp on the email reviewed by Insider.

The billionaire wrote in the email that employees would no longer be permitted to work remotely. He said Twitter expected staff to be in the office for at least 40 hours a week unless they're given approval to work elsewhere, which he'd review.

Musk told Twitter employees, "The road ahead is arduous and will require intense work to succeed."

The Tesla and SpaceX CEO opened the email by saying there was "no way to sugarcoat the message" about the economic climate and its influence on Twitter, which depends on advertising.

Twitter did not reply to a request for comment made outside normal working hours.

Days after Musk finalized his deal with Twitter, employees noticed the company's "days of rest," implemented by the Twitter cofounder Jack Dorsey, had been removed from their calendars, people familiar with the matter told Insider. While Dorsey encouraged staff to avoid burnout, employees of Musk's other companies, such as SpaceX and Tesla, are known to work long hours.

The change in pace at Twitter became apparent after a photo was posted on the social-media platform showing a manager sleeping on the floor at its San Francisco headquarters last week.

Bloomberg earlier reported on the letter.

Read the full email that Musk sent to employees: