Eight hours. That’s the magic number for a good night’s sleep, right? It’s what most of us have always been told and I certainly believed it.
So over the past few months, I’ve been making a real effort to get mine. I stopped telling myself ‘just five more minutes’ while scrolling TikTok at 11.30pm, set myself a very firm alarm (no snoozes allowed!), and actually got under the covers on time. And most nights, I get my eight hours.
But there are still mornings when the alarm goes off and I feel anything but well-rested. Anyone else?
To work out why, I spoke to sleep expert Dr Jemma King, author of Sleep First. When I asked what people most often get wrong about sleep, her answer was immediate: “That it’s all about clocking eight hours.”
Well, there was my first mistake.
It’s not just how long you sleep
The number of hours you spend in bed only tells you so much.
“Time in bed and quality of sleep are two different things, and plenty of people get eight hours of fragmented, poorly timed sleep,” Jemma notes.
Most of us fixate on how many hours we get but when it comes to sleep, our bodies like routine. Going to bed and waking up at roughly the same time each day helps anchor your body clock, giving your body cues about when to wind down and when to wake up.
“Duration matters, but research tracking over 60,000 adults found that the people with the lowest risk of depression and anxiety weren’t those who slept longest, they were those who slept at the same times each night,” she says.
The habits getting in the way of good sleep
Modern life hasn’t exactly made it easy to sleep well.
“We haven’t broken our sleep so much as built a world that works against it, and the good news is that most of those obstacles are within our control and can be removed,” Jemma notes.
Some of those habits are obvious – screens and late nights – but one of the biggest disruptors is that glass of pinot we tell ourselves helps us unwind after a bad day.
“Unfortunately, it’s not true,” Jemma says. “I love a glass of red with dinner, but that glass of wine sedates you, which feels like falling asleep faster, but sedation is not sleep, and alcohol fragments your sleep cycles and blocks REM, the stage where emotional processing and memory consolidation happen.”
Caffeine is a close second as it lingers in your system much longer than most people realise. “It blocks the very chemical that makes you sleepy, and can stay in your system anywhere from 5 to 9 hours depending on your genes, liver health and hormones,” she explains.
Eating a heavy meal too close to bedtime can also affect your sleep in less obvious ways. “Late snacking, especially with sweet foods, also does its damage more quietly, by raising resting heart rate, disrupting gut biome, and by setting up blood sugar crashes that can wake you in the early hours.”
Are you sleeping as well as you think?
Hands up if you ever insisted you slept fine, despite feeling exhausted all day? (Asking for a friend). Jemma says these are some of the signs to look for:
- needing caffeine to feel human
- snapping at people over small things
- brain fog
- afternoon energy crashes
- a drop in sex drive
- getting sick more often
- waking unrefreshed, no matter how early you went to bed
“Irritability is a particularly reliable flag, because fragmented sleep dials down the prefrontal cortex, the brain region that handles emotional control,” she points out.
“If several of those sound familiar, your sleep quantity might be fine but your sleep quality is asking for attention.”
Of course, persistent tiredness can have other causes. If you’re still exhausted despite making changes to your sleep, it’s worth checking in with your GP.
How to make those eight hours count
If, like me, you’ve been too focused on clocking eight hours, Jemma recommends paying closer attention to what happens before bed. Here’s where to start:
- Finish vigorous exercise at least four hours before bed and your main meal at least three hours before bed. Both raise your core temperature and stress hormones at exactly the wrong time.
- In the final 90 minutes, dim the lights, put screens away and swap scrolling for something that genuinely helps you wind down, such as reading, an audiobook or a short breathing practice.
- About an hour before bed, do a quick ‘brain dump’. Write down any worries, tasks or loose ends so your brain isn’t tempted to process them at 3am.
- Keep your bedroom cool, dark and quiet, and aim to get into bed within the same 15 to 30-minute window most nights.
