2020 has not been a good year for mental health. The emergence of a global pandemic has left many people fearing for their lives, stressing over their finances, panicking over the news, and yearning for their loved ones.

While we're still not sure what the mental health toll will be, the World Health Organisation expects levels of loneliness, depression, harmful alcohol and drug use, and self-harm or suicidal behaviour to rise.

Of all the nations in the world, New Zealand took some of the fastest and most drastic measures to COVID-19. And while this 'go early, go hard' strategy saved many lives and ultimately eliminated the virus, the successful measures also came with their costs – not just to the economy but also to public wellbeing.

Roughly halfway through New Zealand's toughest stage of lockdown, which lasted for 33 days, a public survey saw levels of stress, anxiety, and depression rise higher than normal, especially among younger people.

Among the 2,010 respondents, nearly a third scored above the cut-off for moderate to severe psychological distress, and almost 40 percent said their level of wellbeing was low.

It's worth noting the study couldn't distinguish whether it was the lockdown itself that was causing the mental health effects or the broader threat of the pandemic, but it still shows a worrying trend.

"New Zealand's lockdown successfully eliminated COVID-19 from the community, but our results show this achievement brought a significant psychological toll," says psychologist Susanna Every-Palmer from the University of Otago, Canada.

"Substantially increased rates of distress were seen among those who reported having lost their jobs or experienced a reduction in work as a result of the pandemic, those who had potential vulnerabilities to COVID-19, or identified their health status as poor, and those who had a past diagnosis of a mental illness."

On the whole, it was younger people, between the ages of 18 and 24, who appeared to have the toughest time, with almost half receiving a score well above the threshold for moderate psychological distress.

Older folks, on the other hand, seemed to weather the storm much easier, despite being more at risk from the virus and despite being less connected online as a group.

"This is not to say older people were unscathed," the authors explain.

"In our survey, psychological distress was more prevalent among people of all age groups when compared with prevalence in the same age bracket in the NZ Health Survey."

But younger age groups appear particularly vulnerable. This could be because lockdown coincided with fewer daily disruptions and economic impacts for different age groups.

When over 90 percent of the world's students have been impacted by pandemic closures, it makes sense that young people seem to be suffering the most in initial psychological research.

New Zealand's strictest lockdown only lasted for 33 days, with all schools and non-essential businesses shut down and people told to stay at home. That's a very different scenario to what's happening in the US and many other parts of the world, with lockdowns stopping and starting and dragging on for months. But while it's true New Zealand ultimately eliminated the virus, at the time of the survey no one knew that would be the case.

One of the most worrisome findings has to do with women. Unfortunately, while reducing movement and keeping people in the home can save lives in a pandemic, it can also put lives at risk. Consistent with local media reports, the survey found domestic violence had risen during New Zealand's lockdown.

Reported levels of physical assault, sexual assault, harassment, and intimidation in the home were between three and four times higher than normal, according to the survey, matching a similar rise in domestic abuse the world over as lockdown measures continue.

The survey sounds like a lot of bad news when the world really doesn't need any more, but there are some reasons to remain hopeful. Not only was New Zealand's strict lockdown shortened by its success, the majority of respondents in the survey said they could see the positives of remaining in isolation, whether it be for themselves or for society.

Even in parts of the world where lockdown likely won't eliminate the virus, isolation measures have helped reduce its spread and save lives.

In New Zealand, for instance, working from home, spending more time with family, and living in a quieter environment reportedly gave people the opportunity to pause, reflect and consider their priorities, according to the survey.

Obviously, there's only so long you can do this before the novelty starts to wear off, and it'll be interesting to note how mental health is impacted by longer lockdowns in other parts of the world.

Research has only just started, but a recent survey in the United States found a modest negative impact across the board in the early months of the pandemic, with younger adults and those with pre-existing health conditions reporting more psychological distress.

But positively, in this study participants generally felt better at the end of the research than they had at the beginning, which suggests lockdown may take some getting used to.

It might even be helping us cope with the stress of the pandemic. The same survey found hand-washing, social distancing, and masking were associated with better mental health.

In some ways, it's easier to blame all our frustrations on the lockdown instead of the virus itself, but in reality, it's hard to say how the world would be faring mentally if we weren't taking any public health measures during a pandemic.

"It is clear that the consequences of the pandemic will be pervasive and prolonged," says Every-Palmer.

"Governments should make providing mental health support a similar priority to other health measures, such as contact tracing, provision of personal protective equipment, and procurement of ventilators," she adds.

The study was published in PLOS One.