With the threat from the Delta variant bearing down across the United States, it is almost hard to remember the heady days this summer when many of us were experiencing relief, joy, even euphoria as we began to resurface from the pandemic. Barbecues with friends, dinners out, live music, connecting with people face-to-face — all of the antidotes to isolation we had been craving became tangible realities.

During the week of June 14, as vaccinations were becoming widespread and public life seemed to be returning to normal, Gallup classified 59.2 per cent of Americans as “thriving” based on their responses to a survey that asked them to evaluate their lives, the highest average score on that measure in 13 years. Optimism was through the roof.

But now, many people are experiencing a starkly different set of feelings — blunted emotions, spikes in anxiety and depression and a desire to drastically change something about our lives. If this sounds familiar, you might be one of the many people experiencing what we’ve begun to refer to as “pandemic flux syndrome”. It is admittedly not a clinical term, but it seems to capture something about the moment we are living through.

Since June, and that optimistic poll result, the United States has taken significant steps backward in fighting the virus: The prolific Delta variant has led to spikes in Covid cases and deaths, 30 per cent of adults in America remain completely unvaccinated, the Centres for Disease Control and Prevention has reinstated its recommendation to wear masks indoors, and various localities have tightened their Covid-related restrictions. At the same time, many more people are going out to concerts or to dinner, most children are preparing to return to in-person school, and a substantial number of people will return to their workplaces in the autumn, if they haven't already done so.

In a mid-July poll by CBS News of American adults, 62 per cent reported feeling concerned about the spread of the Delta variant, yet 52 per cent also reported feeling hopeful about the near future. In short, people are awash with conflicting feelings as they grapple with the swings and mixed signals of threats, shifting public health policies and uncertain social behaviour.

By midsummer, we began hearing from friends, family and colleagues who were experiencing some combination of acute anxiety, sadness and detachment. Sarah, a 44-year-old production analyst and self-described extrovert from Detroit, told us, “I was so eager to go out and socialise, but now I’m surprised at how often I want to retreat back to home when I actually am out with friends.”

Kevin, a 51-year-old partner at a mid-size law firm in Connecticut, explained: “I was looking forward and holding out hope that things would feel like they’d ‛returned to normal' this spring and summer as face-to-face meetings with clients and colleagues picked up. But now that I am having a lot more in-person meetings, with all of these steps towards — and then away from — the end of the pandemic, rather than alleviating my angst, I feel like it’s exacerbating my anxiety and depression.”

This prolonged liminal state is clearly taking a collective mental health toll, and several distinct psychological processes may be contributing to our unease. It exacts a price, for example, when we are denied “a clearly delineated ‛fresh start’ moment,” explains Katy Milkman, a Wharton School of Business professor and author of the new book How to Change. Milkman adds: “Clearly demarcated fresh starts give us renewed motivation and help us pursue important goals. But for most of us, that clear fresh start hasn’t materialised.”

Second, for many people, our brains and bodies are simply fatigued, and recalibrating to the new circumstances is too much to bear. In part, that is because many of us have been relying on what psychologists call “surge capacity”. As psychologist Ann Masten explained in an interview with science journalist Tara Haelle, “Surge capacity is a collection of adaptive systems — mental and physical — that humans draw on for short-term survival in acutely stressful situations.” But such a response can keep us going for only so long. Eventually, we deplete our surge capacity and need a break so that it can recharge. It looked like many of us were about to get that break, then the moment vanished.

Something called “affective forecasting errors” may also be shaping our moods right now. That phrase, coined by Harvard psychologist Dan Gilbert and University of Virginia psychologist Tim Wilson, refers to the human tendency to be reliably inaccurate when predicting the intensity and duration of our emotions after significant possible future life events, such as serious physical injuries, financial windfalls, or — let's say — emerging from a global pandemic.

Scores of experiments show that this effect works in both directions. For example, people generally overestimate how distressed they will be after a romantic break-up. And when sports fans were asked to predict how they would feel after their team won a major sporting event, they guessed they would be much happier for much longer than they actually were.

How is this relevant to where we are now? We may assume reuniting with friends will be transformatively satisfying, for instance, but maybe it isn’t always. Safi, an 18-year-old British student in Boston admitted to feeling just such a letdown: “When I met up with my mates for the first time in months, it was weird; it was like we didn’t know each other. It was different and kind of disappointing.”

Maybe the dish we’ve been thinking about eating, in person, at our favourite restaurant, for more than a year, will fail to deliver everything we hoped. Maybe the “return to normal” in general underwhelms.

When we asked Nidhi Tewari, a licensed clinical social worker who specialises in trauma and anxiety how people cope with this kind of confusing disappointment, she said: “Many people feel some emptiness, which brings discomfort, and discomfort can make us feel out of control. We then try to regain control by changing what we can, including our jobs, relationships or appearances, somehow redefining our self-concept.”

People who tend towards anxiety might be experiencing strong urges to make major life changes right now, she suggested; meanwhile, people who tend towards depression are feeling compelled to withdraw and shut down. Both reactions are grounded in the desire to escape.

Actually, each of us has experienced both ends of this spectrum: depression and anxiety. One of us tends more towards the melancholic end and longs to crawl under a weighted blanket, pull on some headphones and disappear into endless Grateful Dead bootlegs. The other spins wildly into a twitchy aspiration to change her life entirely —perhaps by becoming a doula and swaddling babies for ever.

Finally, some people feel ashamed and guilty because they think they should be feeling happy right now, when in fact they are sad to be losing pandemic routines that were reducing their stress and that had come to matter to them. Lori Gottlieb, a Los Angeles-based psychotherapist and author of the bestseller Maybe You Should Talk to Someone told us: “During the pandemic, clients were saying things like, ‛I should feel depressed and anxious, but I like this slower pace.’ They liked taking walks in the middle of the day, spending more time with family than colleagues, and having more freedom to work on a schedule that suits their own patterns. A lot of these people were not expecting to be happier during the pandemic, but they were.” Now they feel pressure to tell other people how happy they are that things are — however haltingly — opening up.

All in all, if you are experiencing increased sadness or anxiety along with an urge to dramatically change something about your life — some of the markers of pandemic flux syndrome — be assured that you are not alone. Many people are feeling such tensions. Although human beings are more resilient than we generally appreciate, it will take time for many of us to stably recover, to reflect and recalibrate.

• Amy Cuddy is a social psychologist, the author of Presence: Bringing Your Boldest Self to Your Biggest Challenges, and a faculty member in the Harvard Business School executive education programme. JillEllyn Riley is coauthor of Living the Confidence Code: Real Girls, Real Stories, Real Confidence, and The Confidence Code for Girls: Taking Risks, Messing Up & Becoming Your Amazingly Imperfect Totally Powerful Self