What is the most important thing I can do to improve sleep quality?

According to Dr Dean Miller, the single most impactful change is consistency: going to bed and waking at the same time every day, including weekends. This anchors your circadian rhythm and ensures your body is sleeping during the window it expects to be asleep, maximising restorative quality regardless of any other factors.

How many hours of sleep do I actually need?

For most adults, seven to nine hours is the evidence-based target. Below seven hours consistently is associated with weaker immune responses, more hunger, and reduced cognitive and physical performance. In lab studies where healthy adults slept six hours a night for two weeks, their performance kept falling while they felt only slightly sleepier.

How does poor sleep affect weight loss?

Sleep deprivation reliably increases hunger and food intake, by roughly 250 calories a day in lab trials, and may affect appetite hormones such as ghrelin and leptin, though hormone findings are mixed. In one small trial, dieters lost less than half as much fat on short sleep as on a full night, making good sleep a worthwhile focus for anyone in a weight loss phase.

Are wearables like Whoop and Oura worth using for sleep?

Yes, with appropriate expectations. In a lab study of 53 healthy young adults, Whoop and Oura matched lab sleep staging about 60% of the time, while trained human scorers agree with each other about 83% of the time. They were much better at simple sleep versus wake (86 to 89%), and are useful for total sleep time, resting heart rate, and heart rate variability. Focus on trends across weeks rather than single-day readings, and always weigh the data against how you actually feel.

Does exercising at night ruin your sleep?

Not usually. A review of 23 studies found evening exercise did not harm sleep in healthy adults (Stutz et al., 2019). The one exception may be vigorous exercise finishing within about an hour of bed, so if you train hard at night, leave some wind-down time.

When should I take melatonin for sleep?

In Australia, melatonin needs a prescription unless you are 55 or over and a pharmacist supplies the 2 mg slow-release tablet, so speak to your GP or pharmacist first. If it is recommended, take it approximately one to two hours before your intended bedtime, which mirrors the natural melatonin rise that occurs about two hours before sleep. Taking it at the wrong time, for example in the middle of the night if you wake up, can shift your body clock in the wrong direction and disrupt the following night’s sleep. Only use it after consistent behavioural strategies have been tried, and consult a doctor if considering it for ongoing sleep issues.

How does alcohol affect sleep quality?

Alcohol helps you fall asleep faster but delays REM sleep and makes the second half of the night lighter and more broken, so overall sleep quality drops. Even one or two drinks close to bedtime can delay REM sleep and make the second half of the night more broken. The further from bedtime you drink, the lower the impact on sleep architecture.

How should shift workers approach sleep?

The key is understanding both sleep pressure, the adenosine build-up that makes you feel tired, and your body clock, a circadian rhythm set primarily by light. Most permanent night workers never fully adjust their body clock, so plan around it rather than waiting for it. Use caffeine strategically during the toughest phase of a night shift rather than at the start. Keep the sleep environment dark and cool. Be aware that the most difficult period is often the weekend, when an entrenched night rhythm clashes with normal social life.

Complete Sleep Guide: Chronotypes, Jet Lag & Wearables

Sleep is one of the most researched topics in performance science and one of the most misunderstood in everyday life. Most people know they need more of it. Far fewer understand what actually makes sleep restorative, why so many popular hacks fall short, and what the evidence really says about practical, sustainable improvement.

To cut through the noise, we spoke with Dr Dean Miller, a sleep and exercise scientist with a PhD examining sleep and jet lag in elite athletes, and Director of Chase Science Consultancy, where he works with high-performance athletes, shift workers, and military personnel to optimise sleep and recovery. Dr Miller has also worked with wearable company WHOOP and led one of the wearable studies referenced below, so treat his views on devices as those of someone close to the industry. His answers are clear and refreshingly free of the over-complicated advice that dominates social media.

Whether you are trying to lose weight, perform better, recover faster, or simply stop waking up exhausted, this guide covers what actually matters.

What Is a Chronotype and Does It Explain Why You’re a Night Owl?

If you have spent years forcing yourself out of bed at 5am and never quite adjusted, there is a biological reason for that. It is called your chronotype: your natural tendency toward being a morning person, an evening person, or somewhere in the middle.

“Chronotype is something that can be managed,” Dr Miller explains, “but for evening types, modern society can be quite hard.”

Most people shift slightly across their lifespan. Adolescents tend toward late chronotypes, which is why teenagers persistently stay up too late and struggle to wake for school. In adulthood, we typically settle into one direction or the other. Genetics plays a big role, but environment matters too. Dr Miller has seen swimmers who train at 4am from childhood develop an early chronotype, which suggests routine and light exposure count as well.

Can you train yourself to become a morning person?

To some extent. The most effective lever is light. Getting bright light exposure immediately after waking, with natural sunlight being best but a bright artificial light working when the sun is not yet up, moves your body clock earlier over time. Crucially, this only works with consistency. Waking at the same time every day and seeking morning light creates gradual adaptation; waking at wildly different times each day undoes it.

“If you can, work to your chronotype,” Dr Miller advises. “If you can’t, if you have to be up at 5am, there are things you can do to manage your body clock. But consistency is the foundation.”

The practical takeaway: if you have genuinely tried to become a morning person and it has not stuck, you may simply be working against your biology. Structuring your most demanding work into the hours when your body is naturally more alert is a more sustainable approach than fighting the clock every day.

How Much Sleep Do You Actually Need?

The answer most people have heard, eight hours, is broadly right. But the nuance matters.

“I would say aim for over seven consistently,” Dr Miller says. “If you can do eight, fantastic.”

For athletes, the picture is particularly striking. A study of 175 elite Australian athletes found they felt they needed an average of 8.3 hours per night to feel rested, but averaged about 6.7 hours (Sargent et al., 2021). “Only about 3% of them were actually hitting their own benchmark,” Dr Miller notes. Seven in ten fell short by an hour or more.

Bar chart. 175 elite Australian athletes said they needed 8.3 hours of sleep a night to feel rested but averaged 6.7 hours. Only 3% got the sleep they said they needed, and 71% fell short by an hour or more.

What happens when you consistently fall below seven hours?

The effects are wide-ranging. “Any consistent reduction in sleep is associated with worse immune health,” Dr Miller explains. “And when we’re sleeping less, we’re more predisposed to reaching for unhealthy foods because it’s impacting those hunger hormones.”

There is also a performance trap most people fall into without realising. If you consistently sleep five or six hours, your performance will decline, but it will decline to a new, lower baseline. Because the degradation is gradual and consistent, you stop noticing it.

“You’re not going to notice the decrements because you’re doing the same each day,” Dr Miller says. “But you are operating at a reduced capacity.”

Lab research backs this up. When healthy adults were limited to six hours a night for two weeks, their performance kept falling while they rated themselves only slightly sleepier (Van Dongen et al., 2003). There is an immune angle too: sleeping less than six hours around a flu vaccination is linked to a weaker antibody response, particularly in men (Spiegel et al., 2023).

Evidence-based sleep targets:

Most adults: 7 to 9 hours per night
Athletes: elite athletes report needing about 8.3 hours to feel rested, so aim for 8 or more
Below 7 hours consistently: associated with weaker immune responses, more hunger, and reduced cognitive and physical performance

The Single Most Important Thing You Can Do to Improve Sleep Quality

Before supplements, gadgets, or evening routines, the answer is consistency.

“The most important thing is consistency,” Dr Miller says. “We have these 24-hour biological rhythms called circadian rhythms, the body clock. These rhythms are quite set to light, and our bodies know when they’re winding down for sleep and when they’re going to wake up.”

Sleeping during the window your body expects to be asleep produces the best quality sleep. Irregular bedtimes, sleeping early one night and late the next, disrupt that rhythm and compromise quality even when total hours appear adequate.

“Try to have the same bedtime and same wake-up time where possible, even on weekends.”

The weekend sleep-in is one of the most common ways people inadvertently undermine their sleep quality during the week. Dr Miller’s practical compromise: limit any weekend sleep-in to around 90 minutes, which is roughly one full sleep cycle. “You still get that satisfaction of sleeping in, but you don’t shift your body clock enough to cause problems come Monday morning.”

How Does Light Affect Sleep and What Should You Actually Do About It?

Light is the primary signal that sets your body clock, and most people are using it in reverse.

In the morning: seek light as early as possible after waking. Natural sunlight is optimal, but a bright artificial source works when the sun is not yet up. This anchors your circadian rhythm and signals clearly that the day has started.

In the evening: reduce bright, white, or blue-toned light in the lead-up to sleep. This means dimming overhead lights, switching to warmer lamps, and lowering screen brightness.

“We’re more sensitive to blue-green light in terms of our body clock,” Dr Miller explains. “But even if it’s not blue-green, if it’s just bright white light, it’s still going to have an impact. Warmer light is better.”

What about blue light blocking glasses?

They can work, with a caveat. “The orange-tinted ones that block that blue-green wavelength have scientific support,” Dr Miller says. “But you could also just turn off the ceiling lights. It’s just another tool.”

The evidence is mixed, though: a 2023 Cochrane review of the trials so far could not say whether blue light filtering lenses improve sleep (Singh et al., 2023).

More importantly, the bigger problem with evening screen use is not the light itself. It is the behaviour. “It’s the behavioural aspect of just scrolling and delaying your sleep for an hour. Focus on that first.”

Practical light rules:

Morning: bright light exposure within 30 to 60 minutes of waking
Evening: no bright overhead lights in the hour before bed
Switch to a warm lamp for evening watching or reading
Reduce screen brightness as you move toward bedtime
Blue light glasses may help if you are on screens close to bedtime, but dimming the room is a simpler first step

Why Can’t I Fall Asleep? How to Quieten a Racing Mind

Lying in bed with a brain that will not switch off is one of the most common sleep complaints. Work, tomorrow’s to-do list, anxiety, replaying conversations: the more you try to stop thinking, the louder it gets.

Dr Miller’s primary tool is mental gymnastics, deliberately occupying the mind with a low-stakes absorbing task that crowds out the intrusive thoughts.

“I like to go through the alphabet of football players. Usually when I get to R or S, I’m falling asleep. It’s just little tactics like that, anything that’s going to distract you from the things you don’t want to think about.”

The underlying principle is the same as counting sheep: give your brain something trivial to process, and it stops cycling through everything else.

Other strategies that work:

Diaphragmatic breathing: slow, deep breathing that activates the parasympathetic nervous system and physically calms the body. “You can actually feel your body calming down,” Dr Miller says.
Write it down before bed: if you are mentally running through tomorrow’s checklist or worrying about things undone, writing them on a page before getting into bed can help. In one lab study, adults who spent five minutes writing a to-do list before bed fell asleep faster than those who wrote about what they had already done (Scullin et al., 2018).
Reconsider your bedtime: if you are genuinely not tired, do not force it. “Maybe staying up a little later is actually a better option, because you’re just not falling asleep anyway,” Dr Miller says.

The worst thing you can do is lie in bed frustrated about not sleeping. If you have been awake for 20 or more minutes and feel wired or anxious, get up, do something calm in dim light, reading or gentle stretching, and return to bed only when you feel genuinely sleepy.

Sleep Stages: Should You Worry About REM and Deep Sleep?

Wearables and sleep apps place significant emphasis on sleep stage percentages: REM, deep sleep, and light sleep. But should you actually be making decisions based on these numbers?

“Practically, I wouldn’t,” Dr Miller says plainly. “What I look at is just total sleep time. If you’re maintaining a regular bedtime and wake-up time, your body is going to regulate those stages as needed.”

The deeper principle: consistent sleep duration and timing naturally produce appropriate sleep architecture. Checking stage percentages every day can create anxiety, which can make sleep harder, particularly for people who already struggle to switch off.

“Consistency and duration is going to help with quality and sleep staging,” Dr Miller explains. “If you do see a drastic change in how a device is reporting your sleep staging, it may indicate something else is changing in your physiology. You might be getting sick, or going through a high training load period.”

What to focus on instead of sleep stages:

Total sleep time: are you consistently hitting 7 to 9 hours?
Consistency: are you going to bed and waking at the same times?
Subjective feel: do you wake feeling rested, regardless of what the app says?

How Accurate Are Sleep Wearables Like Whoop and Oura?

Consumer sleep trackers have become ubiquitous, but how much should you trust what they are telling you?

Dr Miller has run studies directly comparing wearable data against polysomnography (PSG), the gold standard of sleep measurement, which uses electrodes to track actual brain wave activity.

“Most commercially available sleep devices are great for measuring sleep and wake, the total amount of sleep,” he confirms. “The difficulty is with sleep staging, particularly detecting brief awakenings within sleep that you might not even realise are happening.”

Sleep staging is hard even in a lab. Trained sleep technicians reading the same recording agree on the stage only about 83% of the time (Rosenberg and Van Hout, 2013). In a lab study of 53 healthy young adults led by Dr Miller, six consumer wearables matched lab staging 50 to 65% of the time (Whoop 60%, Oura 61%), but agreed on simple sleep versus wake 86 to 89% of the time (Miller et al., 2022). Useful, but not lab-grade.

Bar chart. Trained sleep technicians agree on sleep stage about 83% of the time. In a lab study of 53 healthy young adults, Oura matched lab sleep staging 61% of the time and Whoop 60%. For simple sleep versus wake, devices agreed 86 to 89% of the time.

“I would focus on what these devices are reliably good at: total sleep time, resting heart rate, and heart rate variability. Not on making daily decisions based on sleep stage percentages.”

Heart rate variability (HRV): what it actually means

HRV, the variation in time between heartbeats, reflects how well your autonomic nervous system has recovered. Higher HRV relative to your own baseline generally suggests better recovery. But it is highly individual: Dr Miller has seen elite athletes with comparatively low HRVs and everyday people with high ones.

“It’s really important to just compare to your own baseline rather than compare across individuals. I could have an HRV of 100 and you could have an HRV of 50. That doesn’t mean I’m healthier or more recovered than you.”

How to use wearable data well:

Focus on trends over weeks, not single-day readings
A low recovery score on a day you feel great does not mean you cannot perform. Dr Miller has seen athletes set personal bests after nights of poor data
A high recovery score does not mean you should ignore signals from your own body
Use the data as one input, not the final word

Sleep and Weight Loss: The Connection Most People Miss

Poor sleep does not just make you tired. It makes hunger harder to manage.

“When we’re sleeping less, we’re more predisposed to reaching for unhealthy foods because it’s impacting those hunger hormones,” Dr Miller explains.

Early studies suggested sleep loss raises ghrelin (the hunger hormone) and lowers leptin (the fullness signal), but larger reviews find those hormone changes are inconsistent. What is more consistent is the behaviour. A 2019 review of 41 trials in healthy adults found that cutting sleep raised self-rated hunger. In the 8 of those trials that measured food intake, people ate roughly 250 more calories a day, and in the trials that tracked weight, partial sleep restriction was linked to a gain of about a third of a kilo (Zhu et al., 2019).

It also matters while you are dieting. In a small two-week trial, 10 overweight adults ate the same reduced-calorie diet twice, once with 8.5 hours in bed and once with 5.5. They lost 1.4 kg of fat with more sleep but only 0.6 kg with less, with more of the weight lost coming from lean mass instead (Nedeltcheva et al., 2010). It was a short, small study, but the direction is clear. We break down both costs, and what each study actually measured, in does sleep affect weight loss.

Bar chart. In a two-week trial, 10 overweight adults on the same diet lost 1.4 kg of fat with 8.5 hours in bed but only 0.6 kg with 5.5 hours in bed. More of the weight lost on short sleep came from lean mass.

For anyone in a weight loss phase, this creates a compounding problem. Short sleep makes hunger harder to manage, which can make an already demanding process harder to stick to. “It sort of just rolls on to basically most physiological processes,” Dr Miller says.

Tired weeks are when food decisions get hardest, so having them made in advance helps. We built INCHECK FIT to give you a weekly meal plan built to your calorie and macro targets, with no meal logging, so a run of short nights does not turn into a week of guesswork. Those targets work best when your hunger signals are working normally, which good sleep helps support.

The sleep and weight loss connection in practical terms:

Short sleep: more hunger and, in lab trials of healthy adults, about 250 extra calories eaten per day
Poor sleep: increased cravings for high-calorie, energy-dense foods
Short sleep while dieting: in one small trial, less than half as much fat lost on the same diet
Improving sleep is a low-cost change that can make a weight loss phase easier to sustain

If you are in a fat loss phase and sleep has been rough, the INCHECK FIT weekly progress review adjusts your targets based on how your week actually went, so a stall shows up as a trend you can act on rather than a mystery.

How Shift Workers Can Manage Sleep Without Quitting Their Jobs

“The best advice I’ve heard for shift workers is: quit your job and get a new one,” Dr Miller says. “But obviously that’s not realistic for most people.”

Managing sleep as a shift worker comes down to understanding two core biological systems.

1. Sleep pressure (adenosine)

From the moment you wake, a molecule called adenosine accumulates in the brain. The longer you are awake, the more it builds. The only way to clear it is sleep. Caffeine works by blocking adenosine receptors, temporarily masking fatigue without eliminating it. For shift workers, this makes caffeine timing critical: use it strategically a few hours into a night shift when fatigue is peaking, rather than immediately at the start when you are not yet tired.

2. The body clock (circadian rhythm)

Your circadian rhythm runs on approximately a 24-hour cycle and is primarily set by light. Most night workers’ body clocks never fully adjust: in a review of six studies of permanent night workers, fewer than 3% showed full adjustment of their melatonin rhythm, and fewer than one in four adjusted substantially (Folkard, 2008). A single night shift causes little shift at all, so the advice differs depending on how regularly you work nights.

For long-term night workers, the key tactics are: keep the sleep environment dark and cool, seek light at the times that will support your new rhythm, and accept that the toughest period is likely the weekend when social pressures conflict with your body clock.

The caffeine nap: a practical tool for shift workers

Have a coffee immediately before a 20-minute nap. Caffeine starts to take effect around 20 to 30 minutes after drinking it, so it kicks in as you wake, which can reduce post-nap grogginess (sleep inertia) while you still get the benefit of the nap itself.

General napping guidance:

Keep naps to 20 to 30 minutes to avoid entering deep sleep
Before 4pm where possible, to avoid disrupting nighttime sleep
Longer naps are appropriate during periods of high training load or shift work, where total sleep time needs to be made up

The Truth About Melatonin: When It Works and When It Backfires

In Australia, melatonin is a medicine, not a supplement. Most melatonin products are prescription-only. The exception is a 2 mg slow-release tablet that a pharmacist can supply for short-term insomnia in adults aged 55 and over. The TGA has been reviewing these rules, so ask your pharmacist what currently applies.

“Your melatonin is a naturally occurring hormone,” Dr Miller explains. “It kicks in about two hours before you’d usually go to bed. Supplements are essentially the synthetic form of it.”

Used correctly, melatonin can meaningfully support falling asleep (it has a mild hypnotic effect), jet lag recovery when timed correctly, and acute sleep disruption from illness, travel, or time zone shifts.

The critical caveat: timing matters enormously, and getting it wrong can make things worse.

“If you take melatonin at the wrong time, say you wake in the middle of the night and take one, it can actually move your body clock in the wrong direction, making the following night worse,” Dr Miller says.

Melatonin does not just make you sleepy; it also signals your circadian rhythm. Take it at the wrong phase, and you are shifting your body clock in a direction you do not want.

“I would only reach for melatonin if the behavioural boxes are already ticked: consistent sleep schedule, managing light, reducing stimulation before bed, and those aren’t working.”

If your doctor or pharmacist recommends it:

Take it 1 to 2 hours before your intended bedtime
Ensure you have nothing demanding to do after taking it
If you are waking up groggy the following morning, speak to your doctor about the dosage
Do not self-prescribe for ongoing sleep problems. Seek a GP with sleep expertise or a sleep specialist
Avoid melatonin bought from overseas websites, including gummies. TGA testing found some contained far more melatonin than the label said, and some contained none

How to Beat Jet Lag: A Sleep Scientist’s Approach

Jet lag is a misalignment between your internal body clock and the time zone you are in. The primary tool to resolve it is not medication. It is light.

“The timing of light exposure is essential, and it changes depending on where you’re coming from, where you’re going, and how long you’re there for,” Dr Miller explains.

The general principle: identify the light-exposure window that shifts your body clock in the right direction, and avoid light during the window that would reinforce your old time zone.

Left alone, the body clock adjusts by roughly one hour a day travelling east and one and a half hours a day travelling west (CDC Yellow Book, 2026). “If you get the light and avoid sequence right, you can shift your body clock faster than that,” Dr Miller says. “For most long-haul trips, that can mean getting over jet lag in a few days rather than a week.”

Travelling to Europe tends to be more manageable than returning. The afternoon sunlight that comes naturally from sightseeing often works in your favour on the way there. The return trip is a different story.

“When you return from Europe, you’re badly situated for jet lag. People typically take close to a week to recover from the return trip.”

For short-turnaround trips, fly in and fly out, Dr Miller’s advice is simple: “It’s probably not worth doing anything at all. Just get back into your normal rhythm when you’re home.”

Travel fatigue vs jet lag: not the same thing

These are two separate issues. Travel fatigue, the exhaustion that comes from cabin pressure, dry air, disrupted posture, and prolonged wakefulness, is not the same as jet lag. Address it with compression garments on long flights, adequate hydration, avoiding alcohol in the air, and light recovery activity such as a walk or pool session on arrival.

How Alcohol Really Affects Your Sleep

The idea that a drink or two helps you wind down and sleep better is one of the most enduring myths around sleep.

“It helps you fall asleep faster, but the quality is compromised,” Dr Miller says. “It potentially delays some of the restorative stages of sleep.”

Alcohol speeds up sleep onset but reshapes the night. A review of the research in healthy adults found it delays REM sleep at every dose and suppresses it at higher doses, while deep sleep can actually increase in the first half of the night (Ebrahim et al., 2013). As the alcohol wears off in the early hours, sleep becomes lighter and more broken, and you are more likely to wake.

“There is nothing that affects my wearable data more than alcohol,” Dr Miller says, speaking from his own years of personal tracking. “Even one drink, I can see it in the data.”

The implication is not necessarily abstinence. It is timing and awareness. “Further away from bed, the better,” he advises. If you are not ready to cut back, leaving a longer gap between your last drink and sleep will meaningfully reduce the impact on sleep quality.

Frequently Asked Questions

What is the most important thing I can do to improve sleep quality? According to Dr Dean Miller, the single most impactful change is consistency: going to bed and waking at the same time every day, including weekends. This anchors your circadian rhythm and ensures your body is sleeping during the window it expects to be asleep, maximising restorative quality regardless of any other factors.
How many hours of sleep do I actually need? For most adults, seven to nine hours is the evidence-based target. Below seven hours consistently is associated with weaker immune responses, more hunger, and reduced cognitive and physical performance. In lab studies where healthy adults slept six hours a night for two weeks, their performance kept falling while they felt only slightly sleepier.
How does poor sleep affect weight loss? Sleep deprivation reliably increases hunger and food intake, by roughly 250 calories a day in lab trials, and may affect appetite hormones such as ghrelin and leptin, though hormone findings are mixed. In one small trial, dieters lost less than half as much fat on short sleep as on a full night, making good sleep a worthwhile focus for anyone in a weight loss phase.
Are wearables like Whoop and Oura worth using for sleep? Yes, with appropriate expectations. In a lab study of 53 healthy young adults, Whoop and Oura matched lab sleep staging about 60% of the time, while trained human scorers agree with each other about 83% of the time. They were much better at simple sleep versus wake (86 to 89%), and are useful for total sleep time, resting heart rate, and heart rate variability. Focus on trends across weeks rather than single-day readings, and always weigh the data against how you actually feel.
Does exercising at night ruin your sleep? Not usually. A review of 23 studies found evening exercise did not harm sleep in healthy adults (Stutz et al., 2019). The one exception may be vigorous exercise finishing within about an hour of bed, so if you train hard at night, leave some wind-down time.
When should I take melatonin for sleep? In Australia, melatonin needs a prescription unless you are 55 or over and a pharmacist supplies the 2 mg slow-release tablet, so speak to your GP or pharmacist first. If it is recommended, take it approximately one to two hours before your intended bedtime, which mirrors the natural melatonin rise that occurs about two hours before sleep. Taking it at the wrong time, for example in the middle of the night if you wake up, can shift your body clock in the wrong direction and disrupt the following night’s sleep. Only use it after consistent behavioural strategies have been tried, and consult a doctor if considering it for ongoing sleep issues.
How does alcohol affect sleep quality? Alcohol helps you fall asleep faster but delays REM sleep and makes the second half of the night lighter and more broken, so overall sleep quality drops. Even one or two drinks close to bedtime can delay REM sleep and make the second half of the night more broken. The further from bedtime you drink, the lower the impact on sleep architecture.
How should shift workers approach sleep? The key is understanding both sleep pressure, the adenosine build-up that makes you feel tired, and your body clock, a circadian rhythm set primarily by light. Most permanent night workers never fully adjust their body clock, so plan around it rather than waiting for it. Use caffeine strategically during the toughest phase of a night shift rather than at the start. Keep the sleep environment dark and cool. Be aware that the most difficult period is often the weekend, when an entrenched night rhythm clashes with normal social life.

References

Sargent C, Lastella M, Halson SL, Roach GD. “How much sleep does an elite athlete need?” International Journal of Sports Physiology and Performance. 2021;16(12):1746-1757. PMID: 34021090. DOI: 10.1123/ijspp.2020-0896 [Survey, n=175 elite Australian athletes. Abstract read on PubMed 28 Sep 2026.]
Van Dongen HP, Maislin G, Mullington JM, Dinges DF. “The cumulative cost of additional wakefulness: dose-response effects on neurobehavioral functions and sleep physiology from chronic sleep restriction and total sleep deprivation.” Sleep. 2003;26(2):117-126. PMID: 12683469. DOI: 10.1093/sleep/26.2.117 [Laboratory trial, 14 days of sleep restriction in healthy adults. Abstract read on PubMed 28 Sep 2026.]
Spiegel K, Rey AE, Cheylus A, et al. “A meta-analysis of the associations between insufficient sleep duration and antibody response to vaccination.” Current Biology. 2023;33(5):998-1005. PMID: 36917932. DOI: 10.1016/j.cub.2023.02.017 [Meta-analysis. Checked Sep 2026.]
Singh S, Keller PR, Busija L, et al. “Blue-light filtering spectacle lenses for visual performance, sleep, and macular health in adults.” Cochrane Database of Systematic Reviews. 2023;8:CD013244. PMID: 37593770. DOI: 10.1002/14651858.CD013244.pub2 [Cochrane systematic review. Abstract read on PubMed 28 Sep 2026.]
Scullin MK, Krueger ML, Ballard HK, Pruett N, Bliwise DL. “The effects of bedtime writing on difficulty falling asleep: a polysomnographic study comparing to-do lists and completed activity lists.” Journal of Experimental Psychology: General. 2018;147(1):139-146. PMID: 29058942. DOI: 10.1037/xge0000374 [Laboratory trial, n=57 adults aged 18-30. Abstract read on PubMed 28 Sep 2026.]
Rosenberg RS, Van Hout S. “The American Academy of Sleep Medicine inter-scorer reliability program: sleep stage scoring.” Journal of Clinical Sleep Medicine. 2013;9(1):81-87. PMID: 23319910. DOI: 10.5664/jcsm.2350. PMCID: PMC3525994 [Scorer agreement data, 2,500+ scorers. Full text checked Sep 2026.]
Miller DJ, Sargent C, Roach GD. “A validation of six wearable devices for estimating sleep, heart rate and heart rate variability in healthy adults.” Sensors. 2022;22(16):6317. PMID: 36016077. DOI: 10.3390/s22166317 [Laboratory validation, n=53 healthy adults, one night. Lead author is the interviewee. Checked Sep 2026.]
Zhu B, Shi C, Park CG, Zhao X, Reutrakul S. “Effects of sleep restriction on metabolism-related parameters in healthy adults: a comprehensive review and meta-analysis of randomized controlled trials.” Sleep Medicine Reviews. 2019;45:18-30. PMID: 30870662. DOI: 10.1016/j.smrv.2019.02.002 [Meta-analysis, 41 RCTs in healthy adults; the +252.8 kcal a day intake figure is pooled from 8 of them. Abstract (hunger, intake, 0.34kg weight gain) verified 6 Oct 2026 via Europe PMC.]
Nedeltcheva AV, Kilkus JM, Imperial J, Schoeller DA, Penev PD. “Insufficient sleep undermines dietary efforts to reduce adiposity.” Annals of Internal Medicine. 2010;153(7):435-441. PMID: 20921542. DOI: 10.7326/0003-4819-153-7-201010050-00006 [Randomised crossover trial, n=10 overweight adults, 14 days each condition. Abstract read on PubMed 28 Sep 2026.]
Folkard S. “Do permanent night workers show circadian adjustment? A review based on the endogenous melatonin rhythm.” Chronobiology International. 2008;25(2):215-224. PMID: 18533325. DOI: 10.1080/07420520802106835 [Review of six studies. Abstract read on PubMed 28 Sep 2026.]
Therapeutic Goods Administration. Melatonin scheduling and safety information. https://www.tga.gov.au [Regulator guidance. Checked Sep 2026.]
Centers for Disease Control and Prevention. CDC Yellow Book 2026: Health Information for International Travel. Jet lag disorder. https://www.ncbi.nlm.nih.gov/books/NBK620865/ [Clinical travel guidance. Checked Sep 2026.]
Ebrahim IO, Shapiro CM, Williams AJ, Fenwick PB. “Alcohol and sleep I: effects on normal sleep.” Alcoholism: Clinical and Experimental Research. 2013;37(4):539-549. PMID: 23347102. DOI: 10.1111/acer.12006 [Review of studies in healthy volunteers. Abstract read on PubMed 28 Sep 2026.]
Stutz J, Eiholzer R, Spengler CM. “Effects of evening exercise on sleep in healthy participants: a systematic review and meta-analysis.” Sports Medicine. 2019;49(2):269-287. PMID: 30374942. DOI: 10.1007/s40279-018-1015-0 [Systematic review and meta-analysis, 23 studies. Abstract read on PubMed 28 Sep 2026.]

Last reviewed: September 2026 by the INCHECK FIT nutrition team.

Last reviewed: September 2026

Everything You Need to Know About Sleep

What Is a Chronotype and Does It Explain Why You’re a Night Owl?

Can you train yourself to become a morning person?

How Much Sleep Do You Actually Need?

What happens when you consistently fall below seven hours?

The Single Most Important Thing You Can Do to Improve Sleep Quality