By Jen Rose Smith, CNN
(CNN) -- Just before the lockdown began, London-based writer Valentina Valentini made the choice of a lifetime: She agreed to marry her partner. She didn't think twice about it.
A few weeks later, Valentini was struggling with pandemic-related anxiety that made even the most basic decisions seem daunting.
"It was just sort of this anxiety around everything," she said. "Sometimes it can manifest itself in the smallest ways, like 'I don't know what to eat right now.' I can't choose the simplest thing."
Experts say Valentini is not alone in her anxiety and the paralyzing indecision it can cause.
In the United Kingdom, 39% of people who are married or in a civil partnership now report high levels of anxiety, according to the Office for National Statistics. Researchers across Europe have found rising anxiety, depression and other mental health impacts amid the pandemic.
More than 35% of Chinese respondents had generalized anxiety disorder, a study found this month. Nearly a third of Americans are now experiencing symptoms of anxiety disorder, according to early-June data from the Household Pulse Survey, a partnership between the United States Census Bureau and the National Center for Health Statistics.
Those numbers might be shocking, but some mental health professionals say they're not surprised.
"Anxiety often goes up in any moment where our bodies perceive a real threat," said Luana Marques, a psychiatrist and president of the Anxiety and Depression Association of America. "It certainly makes sense in the middle of a pandemic."
For many, anxiety is something that you know when you feel it. The American Psychological Association defines anxiety as an "emotion characterized by feelings of tension, worried thoughts and physical changes like increased blood pressure." Other physical symptoms can include a rapid heartbeat, dizziness, sweating and trembling.
While anxiety is distinct from depression, another mood disorder, it's common to experience symptoms of both at the same time. There are several main types of anxiety disorder, including generalized anxiety disorder, panic disorder and phobia-related disorders.
And while the symptoms of anxiety can be deeply unpleasant, Marques said the emotion is actually an essential tool our body uses to get us out of dangerous situations. "Anxiety, as a biological response, is a state of fight or flight," she explained.
Escaping from a lion? The hypervigilance associated with anxiety can help.
But while that heightened awareness and vigilance makes biological sense, Marques said the emotion also erodes our ability to make well-reasoned choices.
"When you have a lot of anxiety you actually have trouble making decisions. That's something I'm seeing in my clinic," she said. "Patients are having trouble figuring out: 'Is this a good decision or not?' And that's because their brain is not fully on to be able to make decisions."
That's concerning: As the Covid-19 pandemic unfolds, many are facing daily decisions with high stakes for their families' lives and livelihoods.
Fortunately, resources are available for those seeking help. The ADAA has a page dedicated to Covid-related mental health resources, including an online support group, how-to videos and tips on finding a mental health provider that offers telehealth services.