It was a Monday night at precisely 21:09 p.m. when I got a text from an unknown number.

"Hi," it declared.

Curious about the identity of the sender, I opened the message. We'd texted before. The last message in our exchange was dated four months prior — almost to the day.

I'd met the guy on Hinge and we'd moved things over to WhatsApp while we were arranging to meet up in person. But the date never happened. The last message I'd sent him was "are we still on for tomorrow night?" — to which I received no response. Until four months later, that is.

I won't lie, I was pretty confused. But, I was also intrigued as to what this chap could possibly have to say after leaving me on read for so long. After a perfunctory back-and-forth, he sent a selfie and asked me to come over to his place "to watch movies :)".

Suddenly it all made sense. This was a booty call. I politely declined (I was in my pyjamas in bed and didn't feel like getting dressed). "That makes me sad," he replied. "I'm a good cuddler." The conversation fizzled soon after.

The next day, at precisely three minutes past midnight, another guy reared his head from my WhatsApp archive. "Hey," the unsaved number said. "Evening — how are things?"

A cursory glance at our message history showed me he'd messaged six months ago, on March 19. This time, I was the one who'd left him on read.

Two guys in two days had to be some kind of record, right? What the hell was going on? After a couple of messages, he texted saying he was "not sure why I got in touch really." I appreciated his honesty.

"I was confused too," I replied.

We ended up chatting quite a bit after that. But the confusion as to why he'd got back in touch lingered. Wasn't this conversation already buried?

What's an 'archive zombie'?

I am not alone in my confusion. I spoke to five people who've experienced the phenomenon of what I've decided to call 'archive zombies'.

Archive zombies are usually people (usually men) you've met via a dating app who you end up chatting to over WhatsApp or iMessage. For whatever reason, the conversation dies, turns to dust. You archive them, so you don't have to see the cadaver of your dead convo lying in your very much alive WhatsApp chats.

But then the second coming happens. The zombie crawls from the archive and into your new messages. Back from the dead.

During my research into the curse of the archive zombie, I decided to ask my very own zombie why he chose to get in touch and told him I was writing a piece about it. "Haha are you serious?" he asked, before agreeing to confess his reasons for contacting me after six months.

"I mean obvious ones," he began. "Breakdown of other relationships / or people I was seeing." Curiosity was also a factor. "Searched my contacts for 'Hinge' to just remind myself who I had in there," he added. "I will be honest, I moved to London in March, I was serially dating. Three dates a week on average maybe."

Journalist Hannah Price tweeted about a guy she met on Hinge who replied to a WhatsApp message a month and a half later. I asked her about the messages that preceded her archive zombie's resuscitation.

Tweet may have been deleted

"He was being a bit inappropriate so I was like we haven't even met yet," she told me. "And then I said you better start planning the date. And then didn't get a reply until Sunday, so a month and a half later."

After tweeting a screenshot of the message, Price's followers were curious to know what the chap had planned for their date. So, she decided to reply to him. "Drinks?" he said, before adding: "I don't have the biggest of brains."

Tweet may have been deleted

Price isn't the only one. Jo Fisher went on a few dates with a guy she matched with last year.

"Then he said he was too busy, but since then he’s popped up on WhatsApp every four months or so to say hello, ask how I am, and suggest meeting again. We never do. I’m waiting for the next message — I’m about due one!"

Whenever her zombie resurrects their conversation, Fisher replies. "I feel like it’d be rude not to! And I do actually care about how he is," she said. "But I think next time he messages I may have to just ignore."

She's not entirely sure what his reasons are for emerging from the archive crypt — she felt that he didn't seem interested when they met. "Why he keeps coming back I don’t know," Fisher said.

"He once asked why we never met up again. Sometimes he just seems to want to chat," she said. "Last time he suggested we get a drink, after a while I tentatively agreed and then he never messaged back again."

When Charlie Edmunds went on three dates with someone she met online, she received a message from them saying, "I really like you." The feeling was not mutual, so she replied, "Actually I'm not really feeling it, sorry, I don't think we should meet again."

But, that wasn't the end of their interactions. "Months later, definitely over six months, I get a message from this person saying 'I saw this thing and it made me think of you,'" said Edmunds. "It was the sort of thing that might make someone think of me, I didn't think it was just a ruse, so we had a bit of a chat, then came the question: 'Are you seeing anyone?'"

Edmunds wasn't seeing anyone at the time, and was asked by her zombie whether she'd like to meet up again. "I did not want to see this person again, and I felt mildly insulted at the question," she said. "Is the assumption that if I spend six more months dating I'll lower my standards and date someone I previously wasn't interested in? Or is it that I'll see just how rubbish all the other potential dates are, and so rate you more highly than I did before?"

She politely declined and did not inquire further into this person's motives for resuscitating their chats. Edmunds has since decided to take a step back from online dating because she's "not hugely interested in seeing anyone unless they show up with no effort from me and demonstrate that they would make my life better."

Becky Wells was dating a guy, but ended things when she realised after three months he was still going on Tinder dates and hadn't told her. She heard nothing from him — not even a message to check if she got home ok after storming off the night things ended.

But five months later he messaged her. "Oh how was your holiday?" he asked her. "Sure you've found yourself another man by now but let's be friends."

"I told him I have enough friends and he promptly blocked me!" she told me.

It's not all bad, though. In fact, some people have ended up breathing new life into dead conversations.

Naimish Keswani was talking to a guy on Tinder back in March and they got on pretty well. "He was going away for the weekend, so we left it open and decided that we'll talk again once he comes back," he said. "That didn't happen."

Last month, they matched on a different dating app and ended up going on a few dates. "We were both kicking ourselves for not following it up earlier, because now I'm in the UK and he's back home in India," Keswani said.

This story might not have a happy ending, but it's bittersweet. "I gained a friend out of it," he added. "Maybe when I go back [to India] we could start things up again and see where it goes."

As we all know, dating isn't straightforward. I, for one, am guilty of attempting to revive flames that have long since been extinguished. On those occasions, I reach out to people who haunt my thoughts and who I know I'll keep thinking about until I do something about it.

But, trawling your phone by searching for the name of the dating app? That's a little bit different. Sometimes there's a reason things fizzle out.

Archive zombies, beware. Not everyone responds well to seeing a ghost.