(CNN) Some days Diana Calvo Martínez works at the laboratory, moving from microscope to test tube, studying microbes. Other days she's analyzing graphs from her living room, or has her head down writing her thesis from the kitchen table. Occasionally, she's washing the dishes or cleaning the floor.
These may seem like standard activities for someone completing a PhD in environmental biotechnology. What's unusual is that she performs all these tasks in front of an audience of strangers on her laptop screen.
Calvo Martínez, 35, is using Ultraworking, an online "work gym," where people from all over the world gather on a group Zoom call, leaving their cameras on, and work side-by-side in 30-minute cycles.
Each cycle is led by a moderator, who notifies users when the time is up and chairs a 10-minute break during which people can interact. Users currently pay $49 a month for unlimited work cycles available 24 hours a day.
The cycles are designed to encourage concentration and productivity, while also providing structure and company.
For Calvo Martínez they've been invaluable. When the pandemic hit, she worried that she wouldn't be able to juggle childcare with her PhD and researcher role at Arizona State University. Her husband, who works at a health clinic, was only going to get busier.
"I am a mom and there was no daycare, no school, nothing to take your kids to or somebody that could take care of them for you. That was a huge stress for me," she tells CNN.
She started logging on to Ultraworking almost daily, working from 8pm to 2am, while her three-year-old daughter was in bed. With the cycles, she stays motivated and is able to work for longer. Having company helps to keep her awake, offering conversation during the breaks, while having others able to see her stops her from procrastinating or taking a nap, she says.
It has also helped with the strain on her mental health since the start of the pandemic. "I was diagnosed with anxiety and depression, and a big reason was not being able to work or be productive," says Calvo Martínez. "Ultraworking has been one of the key ingredients to making my mental health a little better."
Ultraworking is just one of a number of companies offering virtual coworking spaces. There's also Caveday, which -- for $40 a month -- offers "work sprints" of up to 52 minutes, with guided breaks in between involving stretching, breathing exercises and inspirational chats.
Both companies existed before the pandemic, but lockdowns have spurred their popularity, as more people are working remotely.
"It used to be right for freelancers and people that could control their time," says New York-based Jeremy Redleaf, who co-founded Caveday alongside Molly Sonsteng and Jake Kahana. "Then all of a sudden, when the pandemic hit, it was right for ... almost everybody," he says, adding that the company's membership has grown 800% since March.
Caveday would not disclose its total number of members (neither would Ultraworking), but says they hail from more than 15 countries and are between the ages of 15 and 80. There are artists, entrepreneurs, lawyers, CEOs, best-selling authors, new moms and even Oscar winners, says Redleaf.
"Anything you can do with focus, you can do in the cave," he says, listing some of the more unusual things he's witnessed during sessions -- from pottery to someone roasting a chicken.
Having others able to see you through the camera is meant to recreate the discipline of a traditional workplace. When you're aware people could be watching you, you're less likely to turn on the television, have a nap, or play with your dogs.
"People seem more willing to let themselves down than to let other people down," Sebastian Marshall, CEO of Ultraworking, tells CNN.
He compares it to going to the gym: "You say you'll go to the gym, and then you don't. But if you've got a gym buddy or a personal trainer, you're not going to blow them off."
Finding this sense of accountability has been important for people who relied heavily on office structures pre Covid-19, says Marshall. Like an office, it also offers a social element -- during breaks users may tell each other what they're working on or share tips on productivity.
These online workspaces aim to help their users to achieve peak productivity and enter a state of "deep flow," where they are engrossed in their work. Users are muted during work sessions and asked to turn off their phone and desktop notifications.
Ultraworking consists of two-hour sessions, made up of three 30-minute cycles and 10-minute breaks. It's inspired by the popular Pomodoro technique, a time-management method where work is broken down into 25-minute sessions separated by short breaks.
Caveday opts for work sprints that last between 40 to 52 minutes, based on research that the brain can't focus longer than 52 minutes. Users aren't told the precise length of the session because to enter a state of flow, you need to be "fully immersed in what you're doing, and that only happens when you lose track of time," says co-founder Jake Kahana.
Laura Vanderkam, a productivity specialist and author of "Off the Clock: Feel Less Busy While Getting More Done," says that while scientific studies have come up with different results for how long people can focus for, it's generally accepted that it's no more than two hours. She adds that "breaks are necessary for boosting energy levels."
Short structured work cycles align with the idea that work expands to fill the time available, says Grace Marshall, a head coach at training company Think Productive and the author of "How to be Really Productive."
"Working in shorter bursts effectively gives us mini deadlines to work to throughout the day, and a deadline has a great way of focusing the mind," she tells CNN.
Both experts agree that leaving the camera on can improve productivity. "Humans are social creatures," says Vanderkam, "and some people feel more motivated when they can see that others around them are hard at work too."
For Calvo Martínez, using a virtual coworking space has not only saved her PhD thesis but also her work-life balance. "It's funny because it's a platform for working, but at the same time it encourages you to live a balanced life," she says -- "eat well, exercise and take breaks."
"At first it was a bit strange to be on camera all the time with people you don't know," she says. But over time she has gotten to know the users online at similar times to her and feels comfortable working with them.
"They're basically my friends -- I have a connection with these people, and they have helped me a lot."