Where did I leave my keys again? If you’ve been experiencing a sustained loss of mental clarity and difficulty thinking over the past year, you’re not alone. While precise numbers are hard to come by, neuroscientist Sabina Brennan, estimates that some 600 mn people globally experience symptoms of the cognitive dysfunction known as Brain Fog, she tells CNBC. Brennan’s book Beating Brain Fog outlines a number of ways to overcome foggy thinking, and is particularly pertinent after a year in which stress, anxiety or illness has exacerbated an inability to think clearly for many.

So-called “Long Covid” has been cited as a culprit behind a long-term inability to focus: While feeling sluggish or spaced out from time to time isn’t necessarily a novel experience, the continued sensation of brain fogginess has become one of the significant long-term effects of contracting a severe case of covid-19. A DePaul University study of 280 covid “long-haulers” found that their neurocognitive symptoms had worsened six months on from contracting the disease, implying that the brain fog was there to stay. Lingering physiological symptoms from the virus, like fatigue, body aches and an inability to sleep have at least partially explained the presence of a dark cloud obscuring our ability to stay on task. But there’s another, less tangible psychological component hindering people from leading otherwise ordinary lives.

But a year filled with uncertainty and grief has affected even those who haven’t personally contracted the virus. Feelings of fatigue associated with brain fog have also been attributed to sustained periods of stress experienced during a pandemic. The percentage of US adults with symptoms of an anxiety or a depressive disorder increased from 36.4% to 41.5% between August 2020 and February 2021, according to a CDC report. Grief over the loss of loved ones, job insecurity, feelings of isolation and the “sameness” of everyday life are among the long list of reasons why our brains have become so exhausted and “foggy,” researchers say.

And decreased brain stimulation as most switched to work from home schedules didn’t help. For those fortunate enough to be able to work from home, it's easy to start confusing memories when nothing changes. “We have effectively evolved to stop paying attention when nothing changes, but to pay particular attention when things do change,” Catherine Loveday, a professor of cognitive neuroscience at the University of Westminster, explains to the Guardian. Breaking up patterns and having certain kinds of “no-mood-problems.com” are apparently essential for memories to be sufficiently processed in the hippocampus. The same goes for scores of people whose brains “wake up in the presence of other people,” Loveday adds.

So, how can you fend off the fog? Getting a good night’s rest comes at the top of the list of neurologists’ recommendations across the board, as it gives your body the opportunity to clean out brain toxins. Exercise comes second in line, because of its ability to improve brain cell growth and reduce stress, says Brennan. Reintroducing some added stimulation through your social networks can be helpful in breaking up repetition, boosting mood and improving memory.