Around 7 a.m., Maine Medical Center begins to hum.

Quiet hours end and the fluorescent-lit corridors come to life. Patients wake, some to go home, some to go to surgery. Physicians hit the floor, breezing in and out of rooms with students close behind.

For most, this is the start of the day. But for Marieta Atienza, an overnight nurse at Maine Med, it’s the end.

“It is a very difficult shift,” Atienza said of her 11 p.m. to 7:30 a.m. duty. “You have to reverse your biological clock and tell your body, ‘We’ll pretend we’re in days and then we are actually able to live like being on days.’ “

While most patients are sleeping, Atienza is making her rounds. When her shift is complete, Atienza, who’s worked at Maine Med for 35 years, forces herself to stay awake until her 2 p.m. bedtime.

“I don’t go to bed right away because I think day people, when they work days, they don’t go right to bed. So I just try to reverse it to make it healthy,” Atienza said. “People that don’t work nights have to realize that people like me have to have a consistency — to recover.”