The World Health Organization declared COVID-19 a pandemic now four years ago, on March 11, 2020. It feels like yesterday, last month and decades ago all at the same time.

Running out of toilet paper feels like a distant memory. Wiping down groceries, doing elbow bumps instead of handshakes and being unable to find Clorox wipes in any store its unfathomable that it was really just a few years ago. (And, truly, I cant even remember the other things we dealt with in 2020. It has all blurred together.)

If you can relate, youre hardly alone. All over social media, and in real life, people are expressing the same sentiment that the passage of time feels forever changed.

Research is ongoing to determine how exactly the coronavirus pandemic warped our sense of time, said Cindy Lustig , a professor of psychology at the University of Michigan though its safe to say it did. But a few things are likely contributing to that sense of distortion.

In general, for any event in our autobiographical memory we experience this thing thats called telescoping ... some parts of our memory get stretched out in time, whereas others get squished together, said Lustig.

Additionally, big changes or surprising events create event boundaries, Lustig told HuffPost, Our minds expand the time between different events, and compress time within an event.

So, the beginning of the pandemic, which was a surprising event, seems like forever ago, she explained, while life before the pandemic feels even further away. This is because of that event boundary that the start of the pandemic created.

However, when people try to place the events that happened during lockdown on a timeline, they remember them as closer together than was really the case, Lustig explained something that further adds to this warped sense of time.

Whats more, research says that people experiencing anxiety and depression are more likely to experience telescoping, said Lustig. And its well-established that rates of anxiety and depression were both up during the pandemic.

Lockdowns were both scary and mundane.

The pandemic was a huge change to life on a macro level, according to Lustig. All of a sudden, we were in a terrifying pandemic and couldnt see friends and family or even go to work without risking a potentially fatal illness.

But then at the smaller level ... those changes were to make each day less distinctive, Lustig said. Almost any other time when we have a big shift like that, theres usually a lot of activity that goes on within this shift, too.

But that wasnt the case with the pandemic. In 2020 and even for a large part of 2021, most days looked alike probably something like remote work followed by exercise in your living room, dinner at home and video calls with friends and family, over and over again.

When your days feel the same, your brain lumps that time together , making it seem to pass more quickly, Lustig said. So, while the individual days of 2020 may have felt slow because of their sameness, the year overall zipped by.

Additionally, research suggests that psychological distress, which many experienced during the extremely stressful early days of the pandemic, also contributes to a feeling of time moving more slowly.