“I don’t put off going to bed, more going to sleep,” says Shirley*, 37, a researcher and administrator from South Wales. “I should go to sleep well before midnight to start work at 8 or 9 the following day. But I usually settle down into bed with the light off about 1am. My current sleep time is 3 or 4am.”

Much is written about the importance of getting a good night’s sleep, having a consistent bedtime and setting a morning alarm. Science tells us regular sleep patterns lead to longer lives, lower our chance of developing Alzheimer’s, and, anecdotally, we know that it makes us feel better. So why do so many of us sabotage our sleep by staying up later than we should? 

When HuffPost UK spoke to psychologists about this phenomenon of “sleep sabotage”, most told us there isn’t much research yet into the reasons some of us torpedo our body’s chance to rest and recuperate, while others prioritise it. What they do agree on, broadly, is that a conscious decision to stay up past our own bedtime is closely connected to our mental health.

I can relate. Despite needing to be up for a daily news meeting at 8.30am, my bedtime has been slipping later of late. As I tell Dr Sophie Scott, psychologist and professor of cognitive neuroscience at UCL, I’m often still up in the small hours, watching TV, scrolling social media, or staring into space – conscious of the time, while resisting being governed by it.

Like many of us, she responds, I may be suffering from low-level depression right now, instigated in part by the pandemic and the reality of our confined lifestyles. It’s well known that depression and anxiety can be bedfellows – in this case, literally. “For people lucky enough to have enjoyed stable mental health before lockdown, it is really difficult to maintain when everything is so limited and restricted and you can’t see the people you want to see, you can’t be as active as you want to be, and the world’s got very small,” she tells me.

Even so, Dr Scott stresses she sees delaying bedtime as “more of a symptom than a disposition”, distancing herself from the term “sabotage” for being borderline victim-blaming – “it sounds like you’re labelling someone for doing something that is actually more of a symptom of wider sleep issues,” she says.

This much we do know: stress and anxiety release cortisol which makes sleeping much harder; but get less sleep and your stress levels increase. 

“We see people suffering with anxiety around bedtime, because they’ve struggled to sleep, who actually start to fear going to bed,” says Lisa Artis, deputy CEO of The Sleep Charity, which exists to promote the benefits of a good night’s sleep for our health and wellbeing. “This increases their anxiety further and reduces the chance of falling asleep, which causes a vicious cycle.”

With rates of anxiety so high in millennials, many like me are trapped in it.

Whether spurred on by the pandemic or exacerbated by it, anxiety around bedtime can lead to bad habits and avoiding the thing that might help: bed.

“It becomes such a big thing in people’s lives,” says Dr Scott. “Going to bed and lying there awake is so horrible, that you might well use the strategy of just not going to bed so you don’t put yourself in that situation. We have it in our minds that if we stay up later, we will fall asleep when we do go to bed, which isn’t necessarily true.”

We don’t live – or sleep – in a vacuum. There are external factors at play. A global health crisis is one. Unhealthy work practices are another. The Chinese have a phrase for it, ‘revenge bedtime procrastination’, as highlighted by journalist Daphne Lee in a Twitter post shared by hundreds of thousands. 

As Lee describes it, this is the “phenomenon in which people who don’t have much control over their daytime life refuse to sleep early in order to regain some sense of freedom during late night hours. “I want to steal back my time,” Gu Bing, 33, a creative director from Shanghai, told the BBC in a follow-up article.

A HuffPost colleague expressed similar when, pre-pandemic, she swapped her late bedtime with an ‘early-to-bed’ co-worker as an experiment. “Forget eight hours of sleep,” she wrote of her night owl tendencies. “When I work a long day, sandwiched by a not inconsiderable cross-London commute, I feel constricted if I have anything less than six waking hours to myself in the evenings.”

Bringing this up with a therapist, she realised this came from not seeing her working hours as her own – it felt like the clock only started on her day when she got home at 6pm (some parents say theirs starts later still). The solution, she worked out, was to give herself more space during the day. For all its challenges, the WFH reality of Covid has helped her reset a bit and lean into her own rhythms, she tells me, meaning bedtime is less of a battleground.

Muddying the waters somewhat is Sunday night, when sleep can feel especially elusive, even though it doesn’t come after a busy day’s work for most of us. It does come before one, though, and the stress can lead to sabotage.

I, for one, often find myself awake and wired at 1.20am on a Monday morning – with five hours to go before my alarm! – having spent all of Sunday sitting around doing nothing in particular, and wondering why I’m still up. What I need to do is “put myself to bed”. But my inner parent and child are at odds.

Similarly, Hannah*, 27, a marketing assistant who lives in Wales, finds herself sitting up late when she has no reason to – bathed in the blue light of a screen that – as experts like to remind us – is the last thing that’s conducive to sleep.

“I will stay on my phone generally after ‘bedtime’ and look at unimportant things,” she admits. “I will think of something I should have done at work and look at my emails, see if I missed anything,” she says. “There is never any pressing need for me to do any of those things. The world is not going to fall apart because I haven’t read an email or checked Reddit one last time.”

University lecturer Joseph Topps, 30, knows the feeling, too. “I end up doing the whole ‘just one more’ thing ,whether it be a news article, a page in a book, a YouTube video or a round of whatever game I’m playing,” he says. “Before I know it, it’s well into the small hours of the morning.

Doom-scrolling has escalated in the pandemic and no wonder. Everything and nothing is happening at once – we’re bombarded with information, but isolated. And whether scanning the political or the personal, as Sarah Manavis wrote about in the New Statesman, we are left with more than “dehydrated” eyes.

But basic biology can also take some of the blame. The majority of us actually have sleep/wake cycles spanning longer than 24 hours, Dr Scott points out, which explains why we can be keen to stay up beyond midnight. Put simply, our body clocks and alarm clocks aren’t necessarily in sync.

“Hardly anybody has a sleep/wake cycle that completely corresponds to the 24-hour cycle. Most people have a slightly longer ones,” she says. “If you were removed from all the cues of what time of day it is – sunlight and things like that – you would sleep and wake on a longer timescale than 24 hours. So for most people, it is easier to stay up than it is to wake early.”

And Scott has one final idea to shake out from under the covers: that putting off sleep could be seen as a “fight against” what Freud theorised as Thanatos – or the drive towards death and destruction.

This may sound extreme, but applying the Thanatos theory, sleep is aligned in our minds with a death-like state. We are unconscious while we sleep, after all, and Scott describes going to sleep as an “oblivion” that many of us try to avoid.

“You are lost to sleep and you’re fighting against that,” she says of why some people feel uncomfortable about the idea of knowingly nodding off. It feels like embracing “the end of something”, she says, and it can be anxiety-inducing. 

“Being engaged and awake and alert: those are not things that happen when you sleep. This is the opposite of that. It’s the opposite of embracing oblivion, and the lack of control and lack of awareness that is characterised as sleep.

“People like doing things that make them feel more alive and staying up is a great example of feeling more alive.”

* Some surnames have been omitted to offer anonymity. For more advice on how to sleep better, see the articles and resources in HuffPost’s Sleep Edition.