How to Sleep Better: Why Consistency Beats Duration

The full transcript of this episode is below. Lightly edited for readability.

Kelly: Hey Jemma, thank you so much for joining us on Wellness Simplified. I really appreciate it.

Dr Jemma King: Thank you for having me.

Kelly: I’ve been wanting to do an episode specifically on sleep for a while, but I like focusing on Australian experts, and obviously there are a number of great books out there, but they’re all from overseas experts. Then you came across my LinkedIn feed with your book. I thought, perfect, excellent.

Dr Jemma King: It’s very serendipitous.

Kelly: Indeed. Good timing. Now, before we jump into sleep, I like to let people into the lives of my guests. How do you start your day? Do you have a set morning routine? How do you set yourself up for success?

Dr Jemma King: I travel a lot, so it’s pretty chaotic and unfortunately I don’t have a really good routine. But if I am home, I typically get up really early. My partner’s an early bird — I’ve changed into becoming one too, but naturally I’m a night owl. I’m up at six-thirty and I try to do some form of exercise. I know that in the morning I’m a little useless cognitively, so I push back all my deep thinking till the afternoon, which is unusual — people think at three o’clock they can’t think, but that’s my best time. Three, five, and on into the evening.

One thing I try not to do is grab my phone first thing in the morning, because it’ll set my cortisol off. You have no control over who’s texted you, what you’re going to see, what terrible things have happened in the media. So I really try to protect that first half hour. Then I have coffee — usually my last one of the day, because I’m quite sensitive to it — and a good protein breakfast. Protein instead of simple carbohydrates really sets my blood glucose for the day, and I don’t get the fluctuations that are so correlated with emotional fluctuations. Then I get into social media, catch up on what’s happening while I have my coffee, and start the day.

Kelly: Nice. I really agree with you on that half hour — not just jumping straight in, giving yourself that buffer, especially as women, because if our cortisol spikes too quickly the whole day can be off.

Dr Jemma King: Yeah, you get really dysregulated, and emotionally you’ve got to protect how you prime your day, because when you start the day with catastrophe it sets the lens through which you see the world. I try to look out on green — at my farm we’ve got beautiful birds, it’s quiet — and I try to absorb that, because usually I’m on a plane or in a city, lots of noise and chaos.

Kelly: A quick follow-up — you’re all about optimal performance, moving so much — do you have any little hacks you’ve picked up along the way for living like that and still functioning well?

Dr Jemma King: I kind of gaslight myself, to be honest. If I’m tired or jet-lagged, I don’t look for evidence that I should be feeling sad and overwhelmed — I look for evidence that I’m actually coping quite well. I say to myself, you’ve gotten through this before, you can do it again. If I do start to feel overwhelmed, I’ve got some pretty good protocols: exercise, sleep, eating well, getting off sugar, no alcohol, ring my mum, talk to my kids. I’ve got a pretty good formula.

Kelly: There’s one thing you said there I loved — “I look for evidence that things are doing well.” That’s so key, psychologically. It’s all about where we’re looking for evidence.

Dr Jemma King: People don’t understand that thoughts aren’t ephemeral constructs that mean nothing. Thoughts create chemicals, and those chemicals have biological and psychological consequences. You’ve got to be disciplined about what you let run around in your head. You might think, it’s inside my skull, no one will know, it’s just me and my private thoughts — but it’s not true. When you produce cortisol it emanates out of your skin, there’s chemo-signalling, people pick up your emotions. It colours the lens through which you see the world. If you’re looking for evidence of negativity in yourself, you become reactive, you become closed. You’ve got to be really careful about the contents and quality of your thoughts.

Kelly: I agree so much. We spend so much time thinking about what we’re eating and not nearly as much about what we’re consuming mentally. Your background is actually in stress and performance psychology — you’ve worked with Olympic athletes, special forces, the C-suite. What led you to this deep dive into sleep for your book?

Dr Jemma King: It was kind of accidental. I’m a night owl, I hated sleep, I thought it was boring, I wouldn’t do it — people from my youth are baffled that I now research and write about sleep, because I was a terrible sleeper. But I started studying cortisol and stress, doing big studies with thousands of people, and I saw something in the data I couldn’t ignore: every single person who had a mental health disruption also had a sleep disruption. And every person who didn’t sleep normally would eventually succumb to some form of mental health disruption. That correlation was too strong to ignore.

So I started looking more into sleep. Working with athletes and special forces soldiers — people who don’t have a lot of time or resources, Australian athletes aren’t especially well-resourced, and soldiers on deployment don’t have much access to anything — I thought, what is the greatest, most accessible, free, democratically available, effective performance-enhancing protocol? It came down to sleep. If you want to be faster, smarter, better, quicker, stronger, more emotionally stable, have better cognitive performance — sleep is one hundred percent the place to start. And it’s free, every night. I know a lot of people have sleep issues, but if you get that right, the second and third-order effects are that everything else falls into place. Behavioural change becomes so much easier. When you’re not tired, you feel like eating better, going to the gym, being nice to people.

Kelly: Totally. With all my interviews I end them asking for the one habit, and so far almost everybody comes back to reducing stress and optimising sleep. We overlook the simple, right — we want the fancy, complicated protocol, but it’s often the really simple things that make the biggest difference.

Dr Jemma King: It’s so boring! People spend thousands on longevity hacks, supplements, devices — and honestly, just do what your grandparents said: have a good night’s sleep.

Kelly: I liked how deep you went into the different stages of sleep in the book. If people don’t have a tracker, they’re probably not aware of this — and even if they do, they might not understand what’s happening at each stage. Could you explain that?

Dr Jemma King: Some people really don’t like trackers, think they’re a waste of money — but if you’ve got a serious mental or physical health issue, or feel like you’re not coping with life, I strongly recommend getting a wearable, even for six months, because if you don’t know what’s happening during that imperative part of your day, you don’t know how to change it, or even if you should.

All the sleep cycles are equally important, and they each do something different. You start with light sleep — that drifting state between consciousness and awareness, where alpha brain waves shift, and you can actually have insights during this time. Historically people have used this for creative thinking. It’s also the stage you see a lot of in people with anxiety. Then you move into non-REM sleep — N1, N2. During N2 you see K-complexes and sleep spindles, which we’re learning are important for skill development — if you’re learning to ride a bike or play an instrument, you’ll see a lot of these. I call this stage the brain’s bouncer: if a car door slams or a dog barks while you’re falling asleep, you get a spike of brain activity checking whether it should wake you up or let you keep going.

If you’re okay to keep sleeping, those brain waves protect you so you can get down into deep slow-wave sleep — N3 — which I call the body’s wellness retreat. This is when the majority of your brain-cleaning happens, and when seventy to eighty percent of your human growth hormone gets produced. People think growth hormone is just for kids growing long legs, but adults need it for so many metabolic processes. There’s a window of opportunity in deep slow-wave sleep, primarily in the first two hours before midnight, that’s critical for repair — bone, blood, brain.

Then you move into REM sleep, rapid eye movement — this is when you make sense of the emotional events of the day, when unfinished business gets processed. There’s also a big forgetting component; a lot happens during your day that you don’t need to remember. I call this your midnight librarian at work — folders come in, and the librarian sorts: keep that, chuck that one out. Sometimes the librarian says, I don’t know what to do with this one, I need to wake the boss for instructions — and that’s why people get that two or three a.m. waking at the same time every night. Cortisol has a thirty-minute half-life, so if you don’t have a good protocol for wrangling that thought, a ninety-second wake-up can turn into ninety minutes of lying there in a spiral. This is all happening across roughly a ninety-minute sleep cycle — usually you just have a micro-awakening and drop back down, but some people pop right out and can’t get back to sleep.

Kelly: And do you have recommendations for the ideal percentages people should be aiming for in each stage, for those who are tracking?

Dr Jemma King: Around fifty percent of your sleep architecture should be made up of deep slow-wave sleep and REM combined. Depending on your day — if it was very physically demanding, you might see a slightly higher percentage of deep sleep, maybe twenty-six percent, and less REM. If your day was intellectually or emotionally demanding, you’ll see more REM and slightly less deep sleep. Ideally you want at least two hours or more of these combined. Some people get up to four, which is amazing.

Kelly: And if people notice — say on their tracker — that their deep sleep is fine but REM is low, or vice versa, are there specific things to work on for each?

Dr Jemma King: Yes, and tracking is incredibly important for working out which one’s being affected by which behaviour. If you’re not getting enough deep slow-wave sleep, it could well be alcohol, or eating heavy protein before bed — your body prioritises digesting that rather than getting into deep sleep. I’d recommend having protein at lunch and going vegetarian at night. It could also be exercising too intensely in the four hours before bed — anything above fifty percent of your perceived maximum output will raise your cortisol and core body temperature and delay sleep onset. Do intense exercise earlier in the day, or keep evening movement gentle.

Alcohol absolutely crushes REM sleep, because your body prioritises clearing the toxic byproducts before it lets you into REM. And getting to sleep in those two hours before midnight really matters — if you sleep eight hours but go to bed at midnight or one, the big population data sets say that’s not as good for you. It’s not just how much sleep — it’s when you have it. Bringing your sleep cycle forward is important for getting more of both deep and REM sleep.

Kelly: It’s interesting — a lot of this we’ve known for centuries. My meditation teacher told me years ago that the ancients always said the hours before midnight were critical. We’ve had this information and just overlooked it.

Dr Jemma King: We live in an attention economy where streaming platforms and social media companies hire behavioural scientists like me to work out how to capture people’s attention — and they openly say sleep is their biggest competitor. It’s dopamine hacking us, and it’s really hard to stop. If there’s one thing parents can do to show they love and care about their child’s future, it’s making sure phones don’t stay in their bedroom. What we’re seeing is a huge correlation between sleep deprivation and anxiety and depression — I actually think a lot of the mental health epidemic is, at its root, sleep deprivation.

Kelly: There’s one thing in that section I loved — you talked about directing your subconscious problem solver. Can you talk us through the dream incubation process? And do you have an example of how you’ve used it yourself?

Dr Jemma King: You set an intention before you go to sleep about a problem you want to explore. When you’re conscious, you’re bound by rules — physics, societal rules, your own belief systems. When you fall asleep, or when you’re just waking, those constraints lift and your mind can wander freely, making connections between parts of your memory that don’t normally talk to each other.

Write your intention down on paper, then — depending what you want to do — hold a spoon or a set of keys in your hand, with a metal tray underneath your chair or beside your bed, and let yourself drift into alpha brain waves, into light sleep. When you fall asleep your hand relaxes and the keys drop, the clink wakes you, and you sit with the essence of whatever you felt, smelt, saw — it won’t necessarily make sense or be logical, just jot it down anyway. You can do this falling asleep or when you’re just waking up too.

Kelly: There’s another thing in your book that really stopped me. You quote a study showing irregular sleepers have around a fifty percent higher all-cause mortality risk than people with regular sleep. I thought, whoa. You talk about how duration matters, obviously, but consistency matters more. Can you explain that?

Dr Jemma King: This was quite confronting for a lot of people. You think, I’ve just got to get at least seven and a half, eight hours in — but this huge population dataset says, actually, no. When you look at the biology of what’s happening inside our cells, it makes sense. Every cell in your body has an internal timekeeper — if you imagine hitting the suprachiasmatic nucleus, right at the top of the mouth, that’s a tiny cluster of brain cells that acts as your internal clock, driven largely by light and day cycles. It sends messages to every system in your body: time to upregulate or downregulate, time to grow, time to expel metabolic byproducts. These systems need to know when that’s happening.

If you’re going to bed and getting up at different times, delaying sleep at different times, your body gets confused. From a hunter-gatherer perspective, being up at night with moonlight hitting your retinal cells would have signalled something significant was going on, so your body produces stress hormones just in case. If you’re doing this to your body every day, it keeps getting confused — why am I up, there must be something stressful — and produces cortisol, which has a thirty-minute half-life, so you’re lying there trying to fall asleep with stress hormones still active, which makes you more stressed, in a catastrophic downward spiral.

I like the analogy of a café: if you tell your staff you’re opening on Tuesday but don’t tell them what time to come in or how long their shift is, that’s untenable for anyone — but we do this to ourselves daily. Your cells aren’t doing their jobs properly because they’re trying to work out what’s going on, and stress hormones are expensive.

Kelly: What about “social jet lag”? Can you explain what that is?

Dr Jemma King: Social jet lag is the gap between when you need to go to sleep and when you actually do — the difference between your weekday sleep times and your weekend ones. If you’re fairly regular on weeknights but blow out on the weekend, staying up till 2am, your brain needs consistency, so it’s like you’ve flown three or four time zones without actually going anywhere. You don’t get the holiday, but your body feels the time-zone change — and as anyone who’s had jet lag knows, it can take days to recover, because so many systems rely on that day-night wake-sleep signal. In the book I’ve got a formula for working out your weekday-versus-weekend gap — if it’s a big number, you should probably reassess your social life.

Kelly: Getting practical for a moment — how much leeway do you actually have between weekday and weekend sleep and wake times before it starts affecting your body?

Dr Jemma King: It’s really an individual number, and you’ve got to run mini experiments on yourself. You’re better off getting regular sleep than lots more sleep. If you know you’ve got a big weekend coming, you’re better off picking a later bedtime and keeping it consistent, rather than being all over the place. There’s only so long your body can keep up with the alternative — as I say in the book, Mother Nature’s like the mafia, she comes and collects no matter what. You might think you just can’t lose weight, or you’re having trouble concentrating, or you keep getting colds — and you can often trace it back to inconsistent, insufficient deep slow-wave sleep.

Kelly: This will be a wake-up call for people who think, I’m getting my eight hours, but it’s all over the place day to day. Let’s go into a couple more things — could you talk briefly about how you set up your environment for optimal sleep?

Dr Jemma King: From a hunter-gatherer perspective, it was dangerous to be knocked out for seven or eight hours, unprotected, with predators around. To easily and happily fall into deep sleep, we need to feel safe and secure, the temperature has to be right, and we need enough time without pressing issues on our mind. There’s a whole constellation of psychological, physical, and behavioural things to think about.

In the lead-up to sleep, block out at least two hours for anything stimulating or anything putting bright light into your eyes — try not to have TVs going right up until bed, or doom-scroll. If you have to check your phone at night, turn the screen to the lowest possible brightness, or look at it side-on rather than straight into your eyes. I turn down all the lights in my house to low, orange lighting — I’ve got motion-activated strip lights under the sink and in the hallways so I’m not hit with bright light walking around at night, and a red light in my bedroom, because red doesn’t disrupt your circadian rhythm the way other light does.

I don’t eat anything sugary before bed — Whoop data shows people who eat sugary snacks sleep about twenty-six minutes less on average than people who don’t. If I have anything, it’s a handful of walnuts, non-caffeinated tea, or a bit of cheese — something with tryptophan, which is the precursor to melatonin. I only sleep in natural-fibre pyjamas, cotton sheets — synthetics like nylon trap heat and can be irritating. No fragranced fabric softeners either. And I’ve got an Eight Sleep mattress, which regulates temperature — genuinely one of the best inventions, especially for anyone perimenopausal or dealing with temperature fluctuations with a partner.

I try to downregulate before bed — never have an argument or think about anything stressful. If I feel agitated, I do a brain dump: write down everything, and set a “worry hour” for the next day. Say, at eleven o’clock tomorrow I’m going to think about this, call the accountant, deal with that.

Kelly: I love that. My partner has a brain that just won’t switch off, and he’ll wake in the night thinking about something. The brain dump plus scheduling a worry hour is such a good idea — it’s a bit like Dumbledore’s pensieve, where he empties his thoughts into a bowl so he can pull them out later.

Dr Jemma King: Yes — it’s basically helping your midnight librarian close the loop on unfinished threads. Get a nice heavy-bound book and a good pen, categorise your worries into folders for your librarian. And schedule the worry hour for at least forty minutes after you wake — not right before bed the next day — and put an actual time on it: eleven-fifteen, I’ll make that call. That signals to your midnight librarian that you’re serious about dealing with it tomorrow, it doesn’t need to be sorted at 3am.

And if I still can’t sleep because my mind’s busy, I do cognitive shuffling. You think of a word — say, slumber — and picture unrelated words starting with each letter: shoe, salt, silver, situations, slither. When you run out of S words, move to L, then U. I’ve never gotten past R.

Kelly: I’ve never heard of that. What’s the science — is it because your mind’s engaged just enough, or not engaged enough, to keep you there?

Dr Jemma King: It has to be engaging enough that you’re not playing mental ping-pong, but not so emotionally evoking that you attach a feeling to it. Because the words are unrelated, you can’t form a thread to hang an emotion on — but you can visualise them. I’ve got a theory I call the resource-over-allocation theory, or the brain-rot theory: our hunter-gatherer ancestors went to bed a bit hungry, whereas we go to bed full of resources — high blood sugar — and the brain does what it does best with spare resources: think of everything that could go wrong. We never give ourselves quiet, contemplative time during the day the way our ancestors did, so bed becomes the only time the brain gets to run through its worry list. If you go to bed a little bit hungry, and give your brain something efficient enough to occupy it without being emotionally charged, that’s the best combination.

Kelly: And food timing — you mentioned not going to bed too full.

Dr Jemma King: A PhD student of mine, who’s head of global performance at Whoop, researched time-restricted eating and found that people who ate their last meal at sundown improved across the board — resting heart rate, heart rate variability, respiration rate, sleep duration and quality, fewer disturbances. Three pm was actually the ideal cutoff in her data, though realistically no one’s doing that. I’m all about the middle road — a good meal, laughing with your family, occasional wine, that’s genuinely good for you too, and loneliness is dangerous, it really affects sleep. But restricting your eating window tells your body it’s time to repair, not to keep digesting.

What you eat matters too — there’s a lot of research showing a Mediterranean diet is best for sleep, because it’s low in sugar, natural, high in prebiotics, which your gut bugs turn into a short-chain fatty acid called butyrate — important for the mucus lining of your gut. If that lining breaks down, from alcohol or a poor gut biome, food particles can leak into your bloodstream and trigger an immune response — increased cytokines, blood pressure, temperature — none of which is good for sleep.

Kelly: In an Australian summer, when the sun doesn’t set till eight, that eating-with-sundown approach could be tricky. What do people do about the light side of that?

Dr Jemma King: I’d strongly recommend blackout curtains, or an eye mask if you can’t manage that. We know from daylight saving changes that even a one-to-two-hour shift causes measurable effects — more strokes, more heart attacks, more deaths overall — but if you’re a healthy person, that swing is manageable as long as your other levers are in order. I think of health as a set of levers: sleep is the biggest one, but there’s also exercise, food, social connection, work stress. If you know sleep’s going to take a hit for a night or two, make sure the other levers are on green.

Kelly: You mention supplements in the book, and something interesting about melatonin timing. Could you touch on that?

Dr Jemma King: People get confused about melatonin — they think of it as a sedative, take it, and expect to fall asleep. It’s not that. It’s a signaller — it tells your brain it’s time to start winding towards sleep. Taken at the wrong time it can do nothing, or make you feel terrible the next day. I’m quite cautious about how much people rely on it, especially with kids — unless prescribed by a doctor, I wouldn’t give children melatonin gummies, particularly ones bought online. We’ve seen products with no melatonin at all, and others with up to four hundred times the intended dose, and a real rise in kids being hospitalised from poisoning. There’s so much melatonin does in the body that we don’t fully understand yet.

If you’re a night owl trying to shift your cycle earlier, taking melatonin at, say, eight o’clock can help start signalling sleepiness earlier — but taking it in the morning, or very late at night, expecting it to knock you out, doesn’t work like that.

Kelly: You’ve touched on your morning routine — what does your night-time routine look like? And has there been a new habit you picked up while writing this book that’s surprised you?

Dr Jemma King: Light exposure has been the big one for me. There’s a strong correlation between how much daytime light you get and how susceptible you are to evening light — I talk in the book about not sleeping with “ALAN,” artificial light at night. An experiment on office workers found that those who got good morning light were far less susceptible to their melatonin being pushed back by evening artificial light. Eye colour and age matter too — younger, blue-eyed people are more susceptible; older, dark-eyed people less so. I’ve got very fair skin and used to avoid the sun entirely, sunglasses on no matter what — now I try to get sun into my eyes in the mornings instead.

I’m careful about turning down lights and screens in the evening, and about alcohol — I love a glass of red, but I know how much it affects my sleep, so I’ve cut back significantly, save it for special occasions. Food’s the same — I try not to eat heavy protein at night, go vegetarian for dinner, and I’m strict about avoiding MSG.

Kelly: With kids and a busy work life, timing meals early can be tricky — you get home, activities, dinner. How did you manage that?

Dr Jemma King: My kids are grown and moved out now, but it was genuinely hard while they were young — I was a single mum, studying and working, with three kids in different places. Meal prepping was huge for me. I banned junk food after school, because otherwise they’d snack and then not be hungry until later, and dinner would become a fight — so they could eat what was in their lunchboxes when they got home, and I’d try to have dinner early. Because I was doing my PhD, I needed them in bed so I could get back on the computer. I’d meal prep on Sundays — easy basics with a lot of vegetables on top.

Kelly: Bringing it all together — I’d love you to talk about experiments. I’m a big believer in running small health experiments in my own business. What would be an experiment listeners could try this week, whether they have a wearable or are just tracking how they feel?

Dr Jemma King: If you’ve got a wearable like Whoop, you can run mini experiments in the app and get monthly reports. Pick one thing you’re going to change — maybe your diet, or the timing or type of exercise. If you don’t have a wearable, it’s still doable, and I’ve got instructions in the book. Pick something that’s not sleep itself: do you want to lose weight, increase cognitive performance? You could get a reaction-time app on your phone — they’re free.

Baseline yourself for a week with no intervention: rate yourself one to ten on whatever dimension you’re looking at — mood, motivation, energy, how often you argue with people, cravings, how much you vape. Then commit: for two weeks, including weekends, you’re in bed asleep by ten every night, nothing else changes. Track it again afterwards and see where you land. It’s free, it’s two weeks of your life, and I guarantee you’ll see movement in whatever you’re tracking.

Kelly: I love the reaction-time idea — testing before and after.

Dr Jemma King: They’re called psychomotor vigilance tests — used on mine sites, in aviation. Your reaction time is a good indicator of how your brain’s functioning, so it’s tangible and easy to improve. Sleep well and your reaction times improve; get tired, and it’s one of the first things to go.

Kelly: One I forgot to ask, and you do cover this in the book — if your partner has poor sleep and it wakes you up, how do you deal with that?

Dr Jemma King: A lot of people do a “sleep divorce” — separate beds. I don’t think that’s a great idea, because affection, sex, and oxytocin are some of the best cortisol antidotes, and if you’re not getting that, your cortisol can stay elevated, particularly for women. I read recently that if a woman gets one extra hour of sleep, she’s more likely to want and initiate sex the next day — so, for the men listening, let her sleep in, or get her to bed earlier.

Kelly: And it’s cyclical too — good sex leads to better sleep.

Dr Jemma King: Completely — it’s all that oxytocin-cortisol interaction, one of the best ways to clear stress hormones. As for the actual question of mismatched sleep needs between partners — we try to go to bed at the same time every night, because so many friction points come from not doing that. I’m naturally a night owl and would stay up much later left to my own devices, but because my partner’s up at six, I’ve been sort of forced into it, and it’s actually been better for me. If you both commit to going to bed together at a set time, so many other arguments — over the dishwasher, over labour, over money — just dissolve, because you’re not both exhausted, you’ve got a clear head, and you’ve had sex. If you can do anything, try to go to bed at the same time together.

Kelly: Two final quick questions. First — I always like to leave people with one habit. We’ve covered a lot of ways to optimise sleep — if listeners could try just one thing this week, where should they start?

Dr Jemma King: It has to be sleep consistency. Anchor your wake time. Get up at the same time — say six — and don’t nap during the day, even if you feel awful, because napping is what forces you back into an inconsistent pattern. You should get natural sleep pressure around sixteen hours after your first light exposure, so plan to be in bed around that time. Anchor your wake time — that’s the one thing.

Kelly: And finally — how do people find the book? I’ve got my copy here — thank you for sending it — and where do people find you and your work?

Dr Jemma King: The book’s in every bookstore, and coming out on Audible too — just search for it on Amazon or Booktopia. If people want to find me, I post most of my research and work on LinkedIn — Dr Jemma King PhD — and I’ve got a website too. Just Google Dr Jemma King. I share a lot on human behaviour, stress, sleep, and behaviour more broadly.

Kelly: Beautiful, amazing. Thank you so much — I’ve really enjoyed this, and I’m going to go run that experiment myself this week. Thank you for your time, I appreciate it.

Dr Jemma King: Thanks so much for having me. Fantastic.

Kelly: Bye, thank you.