The older I get, the more I love my bed. It’s not unusual to find me propped against the pillows at 8.30pm, ready to decompress and nestle down for the night’s duration. My late mother’s words ring in my head: “You’ll be desperate to get into your bed one day!” She was right. I am.

So I was nothing less than intrigued when I recently read that actress Dakota Johnson likes to sleep for up to 14 hours a night. She says sleeping is her number one priority and gives her greater clarity in life. She also partakes in transcendental meditation and enjoys a bath at any time of the day – this woman knows a thing or two about keeping things chilled.

And I’ve always been staggered by my own teenagers’ ability to lie in bed for inordinate lengths of time. It bemuses me that they can remain comatose while dogs bark, postmen ring the doorbell, my husband bellows that he’s lost his keys and a fire engine belts past their window, sirens wailing.

Like many of us, I have a complicated relationship with sleep. While I love getting into bed, I wouldn’t say I always have a full night’s kip, so when I decided to experiment with staying horizontal for longer than my usual stretch of shut-eye, I immediately felt the pressure of the challenge, which – guess what – kept me awake. Usually, I can notch up eight to nine hours, with the odd intermission for a wee, but sleeping any longer seemed nigh on impossible.

Professor of circadian neuroscience at Oxford University, Russell Foster, says: “The National Sleep Foundation states that the healthy sleep range is between six and 10.5 hours a night; seven to eight hours is average but one size does not fit all. We humans are variable creatures and so it’s up to the individual to decide how much they need to function well.

“A few indicators that something is amiss might be if you require an alarm clock to wake you up, or if you oversleep extensively on free days, or you crave caffeinated drinks, or you feel tired and ratty throughout the day, or you find yourself doing over impulsive things…then you probably need more rest. But if you are doing okay on less than the average amount, that’s absolutely fine.”

Foster also points out that there is a huge difference between sleepiness and fatigue. “Sleepiness is cured by getting enough sleep,” he says. “Fatigue is when a person feels overwhelming tiredness, lack of motivation, even depression. This can suggest an underlying health issue – the classic one these days is long Covid. If suddenly you find you are sleeping a lot more, it’s worth getting a health check.”

In his book Why We Sleep, neuroscientist Matthew Walker informs us that teenagers experience a significant shift in their circadian rhythm, meaning that the rise in melatonin (the hormone which helps us to sleep) moves to many hours later.

“As a consequence, the 16-year-old will usually have no interest in sleeping at 9pm,” he explains. “Instead, peak wakefulness is usually still in play at that hour. By the time the parents are getting tired, as their circadian rhythms take a downturn and melatonin release instructs sleep – perhaps around 10 or 11pm – their teenager can still be wide awake.”

So, it’s not that teenagers have the ability to sleep forever, they are more likely to be night owls, finally throwing in the towel when I’ve already been in bed way before News at Ten.

It’s no wonder they have the ability to doze till lunchtime. Nonetheless, Foster adds that some adults can also sleep for very lengthy periods. It’s just the way they are wired.

“Sleep is triggered by exposure in the brain to the molecule, adenosine. If a person has sensitive receptors to adenosine, they are likely to sleep longer.

“Unfortunately, it’s not really possible to train yourself to sleep more than your usual amount because there are two main drivers that influence this: your own biological clock, and your intuitive approach to sleep – which basically means, the longer you have been awake, the greater the need for sleep.”

Age has some relevance too. Again, while everyone has their own patterns, older adults are more likely to experience fragmented quality and quantity of sleep. Medications and illnesses play a role but for most of us, the culprit is a weakened bladder. I can relate to that. The best thing I ever did was to install an ensuite bathroom in my home.

Walker says that sleep change with advanced age is affected by circadian timing: “In sharp contrast to adolescents, seniors commonly experience a regression in sleep timing, leading to earlier and earlier bedtimes. The cause is an earlier evening release and peak of melatonin as we get older, instructing an earlier start time for sleep.”

That’s fine unless, like me, you want to go to the cinema or a concert and find yourself nodding off before the halfway point. And heaven forbid if I have more than a glass of wine with my evening meal. I’m dozing on the sofa or, more alarmingly, in the bath. My husband has often been known to bang loudly on the bathroom door while yelling: “You awake in there?!”

Foster confirms that “sleep anxiety” is a recognised condition, with millions of people fretting about whether they are getting enough. His sensible advice is to stop worrying.

Waking up in the night is perfectly normal, but the key is helping yourself to get back to sleep, so a relaxing environment and tools like mindfulness are useful.

Foster adds, “Exposure to light, and doing exercise, especially in the morning, are beneficial for better sleep, and there is some interesting data that suggests dog owners have better quality sleep. It’s to do with the companionship that dogs give us and the fact you’re outdoors with them every day.”

So, if I really want to sleep like Dakota Johnson, or even a teenager, maybe I need to walk my dogs more, have lots of baths (but never nap in them), meditate, not drink anything after 6pm so I don’t wee at 2am, avoid being anxious or ill, and perhaps play Call of Duty on the Xbox late at night so I snore till midday. It all sounds suitably exhausting.