113 plain-English guides to how sleep works, why it goes wrong and what helps. Every guide links to the research and health sources behind it.
- Sources linked in every guide
- Practical next steps
- Matching calculators
- 113 guides
Most Read Sleep Guides
The guides readers find most often in search.
- PopularFalling asleep
Why Can't I Fall Asleep?
Ten common reasons sleep will not come, and what actually helps for each.
Read guide - PopularFalling asleep
Why Do I Wake Up At 3 AM?
Seven common causes of waking in the early hours and how to get back to sleep.
Read guide - PopularSleep disorders
What Causes Sleep Talking?
Why people talk in their sleep, how common it is and when it is worth checking.
Read guide - PopularSleep products
Do Smart Pillows Work?
What smart pillows can and cannot do, from sleep tracking to snore nudges.
Read guide - PopularFalling asleep
The 10-3-2-1-0 Sleep Rule
What each number in the rule means and how much evidence supports it.
Read guide - PopularSleep disorders
Is The STOP-Bang Questionnaire Accurate?
How the STOP-Bang questionnaire is scored, how accurate it is and what a score means.
Read guide
Sleep Science And Dreams
How sleep works: stages, cycles and dreams.
- Sleep science
How To Get More Deep Sleep
What deep sleep does, why it falls with age and which habits help.
Read guide - Sleep science
What Is Deep Sleep?
What stage N3 is, when it happens, what it does and how it changes with age.
Read guide - Sleep science
Why Do We Dream?
The main dream theories, how strong the evidence is and why symbol books are shaky.
Read guide - Sleep science
Sleep Timing Myths
Nine popular sleep timing beliefs checked against the research, with a verdict for each.
Read guide - Sleep science
Deep Sleep vs REM Sleep
A side-by-side comparison of deep and REM sleep: timing, brain, body, jobs and why you need both.
Read guide - Sleep science
Does The 90-Minute Rule Work?
An evidence check of planning sleep in 90-minute cycles, with a worked example.
Read guide - Sleep science
What Is Sleep Pressure?
How the urge to sleep builds, what adenosine, caffeine and naps do, and how to use it.
Read guide - Sleep science
What Is REM Sleep?
What happens in your brain and body in REM, when it comes and what research says it does.
Read guide - Sleep science
How To Get More REM Sleep
Why REM comes late in the night and what protects it or cuts it short.
Read guide - Sleep science
How Sleep Works
Sleep pressure, the body clock, stages and cycles: how a night of sleep is built.
Read guide - Sleep science
Dreams Explained
Why we dream, why dreams fade, how to remember them and when nightmares need help.
Read guide - Sleep science
The 4 Stages Of Sleep
The four stages, what each one does and how they repeat through the night.
Read guide - Sleep science
What Happens During A Sleep Cycle
What happens in each sleep cycle, and why waking at the end of one feels easier.
Read guide - Sleep science
What Stage Of Sleep Do You Dream In?
Most dreams happen in REM sleep, but not all. When dreams happen and why.
Read guide - Sleep science
Lucid Dreaming Techniques
Techniques for noticing you are dreaming, from reality checks to dream journals.
Read guide - Sleep science
Scary Dreams And Nightmares
Why nightmares happen, how common they are and when to talk to a doctor.
Read guide
Falling Asleep And Staying Asleep
Why sleep will not come, why you wake up, and what helps.
- Falling asleep
Insomnia: Symptoms, Causes And Treatment
What insomnia is, its types and causes, how it is diagnosed and how it is treated.
Read guide - Falling asleep
CBT-I Explained
How cognitive behavioral therapy for insomnia works, step by step, and how to find it.
Read guide - Falling asleep
Sleep Restriction Therapy
How the CBT-I sleep window is set, what trials show, side effects and who should not do it alone.
Read guide - Falling asleep
How To Fall Asleep Fast
Twelve techniques for falling asleep, compared by how much evidence supports each.
Read guide - Falling asleep
Why Do I Keep Waking Up At Night?
Common reasons you wake in the night, how to get back to sleep and when to see a doctor.
Read guide - Falling asleep
Why Can't I Fall Asleep?
Ten common reasons sleep will not come, and what actually helps for each.
Read guide - Falling asleep
Why Do I Wake Up At 3 AM?
Seven common causes of waking in the early hours and how to get back to sleep.
Read guide - Falling asleep
How To Beat Insomnia
Seven steps from sleep habits to CBT-I, the first-line treatment for insomnia.
Read guide - Falling asleep
Insomnia vs Anxiety
How to tell insomnia and anxiety apart, and how each one feeds the other.
Read guide - Falling asleep
Can Sleep Tracking Make Insomnia Worse?
When watching your sleep data makes sleep worse, and how to use a tracker well.
Read guide - Falling asleep
Sleep Hygiene 101
Everyday habits that make it easier to fall asleep and stay asleep.
Read guide - Falling asleep
10 Bad Sleep Habits
Common habits that quietly cut into your sleep, and simple swaps.
Read guide - Falling asleep
The 10-3-2-1-0 Sleep Rule
What each number in the rule means and how much evidence supports it.
Read guide
Timing, Naps And Wake-Ups
When to sleep, when to wake and how naps and alarms fit in.
- Timing, naps
Best Time To Sleep
Ideal bedtimes by age and body clock, and why a steady schedule matters most.
Read guide - Timing, naps
Best Time To Wake Up
How to pick a wake-up time from your sleep need, cycles and body clock.
Read guide - Timing, naps
How To Get Rid Of Sleep Inertia
Why you wake up groggy, how long it lasts and which fixes have evidence.
Read guide - Timing, naps
Is Hitting Snooze Bad?
What lab studies and app data show about snoozing, and a better alarm plan.
Read guide - Timing, naps
20-Minute vs 90-Minute Nap
Short naps versus full-cycle naps: alertness, grogginess and night-sleep cost.
Read guide - Timing, naps
Biphasic Sleep
Sleeping in two parts: common schedules, what research shows and who it suits.
Read guide - Timing, naps
Social Jet Lag
The gap between your body clock and your schedule, and how to close it.
Read guide - Timing, naps
Why Sleep Regularity Matters
The Sleep Regularity Index explained, and what steady sleep times are linked to.
Read guide - Timing, naps
How To Recover From Sleep Debt
How long sleep debt takes to repay, what lab studies show about catch-up sleep and a gradual plan.
Read guide - Timing, naps
Signs Of Sleep Deprivation
The common signs of too little sleep, the safety risks and when to talk to a doctor.
Read guide - Timing, naps
How To Recover From An All-Nighter
A next-day plan for naps, caffeine and driving safety after a missed night, plus a three-night recovery outline.
Read guide - Timing, naps
Stages Of Sleep Deprivation
What research says happens at 24, 36, 48 and 72 hours without sleep, with a safety box.
Read guide
Sleep Need And Sleep Debt
How much sleep you need, and what happens when you get less.
- Sleep need
How Much Sleep Do You Need?
Hours by age, why needs differ, and how to find the amount that is right for you.
Read guide - Sleep need
Is 7.5 Hours Of Sleep Enough?
A verdict table for 6, 7, 7.5, 8 and 9 hours, with age ranges and signs you need more.
Read guide - Sleep need
Is 7 Hours Of Sleep Enough?
Why 7 hours is the adult floor, who needs more and how to tell if it is enough for you.
Read guide - Sleep need
Is 6 Hours Of Sleep Enough?
What studies show about 6 and 6.5 hour nights, who might be fine, the risks and how to get to 7 hours.
Read guide - Sleep need
How Much Sleep Do Older Adults Need?
Sleep needs at 50, 60 and 70 plus, what changes with age, common problems and what helps.
Read guide - Sleep need
Is 5 Hours Of Sleep Enough?
What 3, 4 and 5 hour nights do, crash risk by hours slept and how to build sleep back up.
Read guide - Sleep need
How Much Sleep Is Too Much?
What counts as too much sleep, common causes, what long-sleep studies really show and when to get checked.
Read guide - Sleep need
Average Hours Of Sleep
Survey numbers from the CDC, BLS and Gallup, why they differ and how to work out your own average.
Read guide - Sleep need
How To Calculate Hours Of Sleep
The sleep time formula, how to count across midnight, worked examples and a diary.
Read guide - Sleep need
What Is Sleep Debt?
How sleep debt builds, how long it takes to repay and whether weekend lie-ins help.
Read guide - Sleep need
Sleep Deprivation
Signs and effects of too little sleep, drowsy driving risks and how to recover.
Read guide - Sleep need
Waking Up Tired After 8 Hours
Why a full night can still leave you tired, and what to check first.
Read guide - Sleep need
Can You Train Your Body To Need Less Sleep?
What research says about cutting your sleep need, and what really happens.
Read guide
Body Clock And Shift Work
Sleep schedules, night shifts and the body clock.
- Body clock
Circadian Rhythm Explained
How your body clock works, what throws it off and how to reset it.
Read guide - Body clock
Chronotypes Explained
Night owls, early birds and the science behind chronotypes, including social jetlag.
Read guide - Body clock
Why Your Sleep Schedule Keeps Failing
Seven body-clock reasons a new bedtime does not stick, with fixes.
Read guide - Body clock
How To Sleep After A Night Shift
A practical plan for sleeping during the day after a night shift.
Read guide
Sleep Disorders
Symptoms, risks and when to see a doctor.
- Sleep disorders
Sleep Apnea Guide
What sleep apnea is, its symptoms, how it is tested and the main treatment options.
Read guide - Sleep disorders
Sleep Apnea Treatment Options
CPAP, oral appliances, surgery and more, compared by who each one suits.
Read guide - Sleep disorders
Sleep Apnea Health Risks
What untreated sleep apnea can do to your heart, mood and daytime safety.
Read guide - Sleep disorders
Sleep Apnea Screening
How screening works, from STOP-Bang and Epworth to home tests and sleep studies, and what each can show.
Read guide - Sleep disorders
Home Sleep Apnea Test
How a home test works, who it suits, how accurate it is and what the results mean.
Read guide - Sleep disorders
What Happens During A Sleep Study?
The night step by step: sensors, sleeping in a lab, how to prepare and when results arrive.
Read guide - Sleep disorders
How To Read Sleep Study Results
What AHI, oxygen nadir, arousal index and sleep stage numbers mean, with normal ranges and questions to ask.
Read guide - Sleep disorders
How To Get Used To CPAP
Mask, dryness, pressure and noise fixes, what helps people keep using CPAP and when to call your provider.
Read guide - Sleep disorders
What Causes Sleep Apnea?
What causes sleep apnea, the risk factors you can and cannot change, how common it is and how to lower your risk.
Read guide - Sleep disorders
Sleep Apnea Symptoms
What sleep apnea sounds and feels like, daytime signs, snoring versus apnea, and signs in women and children.
Read guide - Sleep disorders
Alternatives To CPAP
Oral appliances, positional therapy, weight loss, nerve stimulation, surgery and exercises, with what the evidence says.
Read guide - Sleep disorders
When To See A Sleep Specialist
Signs that call for a sleep visit, what a sleep doctor does, how it differs from a GP and what to bring.
Read guide - Sleep disorders
Sleep Apnea And Weight Gain
How sleep apnea and weight gain drive each other, and what breaks the cycle.
Read guide - Sleep disorders
Is The STOP-Bang Questionnaire Accurate?
How the STOP-Bang questionnaire is scored, how accurate it is and what a score means.
Read guide - Sleep disorders
Why Do You Snore?
Why people snore, when snoring needs a doctor and what actually helps.
Read guide - Sleep disorders
Narcolepsy Explained
The main symptoms of narcolepsy, how it is diagnosed and how it is managed.
Read guide - Sleep disorders
Restless Legs Syndrome Symptoms
How to recognise restless legs syndrome and when to see a doctor.
Read guide - Sleep disorders
What Causes Sleep Paralysis?
Why you can wake unable to move, what triggers it and how to reduce it.
Read guide - Sleep disorders
Sleepwalking Causes
What causes sleepwalking, how to keep a sleepwalker safe and when to get help.
Read guide - Sleep disorders
What Causes Sleep Talking?
Why people talk in their sleep, how common it is and when it is worth checking.
Read guide - Sleep disorders
Signs Of A Sleep Disorder
Signs that tiredness may be a sleep disorder rather than a busy life.
Read guide
Sleep And Health
How sleep affects mood, pain, immunity and more.
- Sleep
Foods That Help You Sleep
What the evidence says about foods, drinks and meal choices for sleep.
Read guide - Sleep
Alcohol And Sleep
What alcohol does to your night: REM, waking, sleep apnea and better ways to wind down.
Read guide - Sleep
How Late Should You Eat Before Bed?
How long before bed to stop eating, with the evidence on reflux, blood sugar and hunger.
Read guide - Sleep
How Sleep Affects Your Health
How poor sleep is linked to the heart, brain, mood, weight, immunity and more.
Read guide - Sleep
Does Lack Of Sleep Cause Weight Gain?
What large studies and trials show about short sleep, appetite and weight, without diet advice.
Read guide - Sleep
Sleep And Mental Health
The two-way link between sleep and depression, anxiety, bipolar, PTSD and ADHD.
Read guide - Sleep
Sleep And Dementia Risk
What studies show about short sleep, sleep apnea and dementia, why cause is unproven and what helps.
Read guide - Sleep
Sleep And Depression
How depression and sleep affect each other: insomnia, oversleeping and when to get support.
Read guide - Sleep
PTSD And Sleep
Why trauma disrupts sleep, how nightmares and hypervigilance work, and the treatments clinicians use.
Read guide - Sleep
How Sleep Affects Your Emotions
What research shows about sleep loss, mood and emotional control.
Read guide - Sleep
Does Poor Sleep Raise Cancer Risk?
What the evidence shows about poor sleep, night shifts and cancer risk.
Read guide - Sleep
Why Poor Sleep Makes Pain Worse
Why sleep loss lowers pain tolerance, and how better sleep can help.
Read guide - Sleep
Sleep And The Immune System
How sleep supports your immune system and what short sleep does to it.
Read guide - Sleep
Sleep And Digestion
How sleep and digestion affect each other through the gut-brain link.
Read guide - Sleep
Poor Sleep And Inflammation
How short or broken sleep is linked to inflammation, and what helps.
Read guide - Sleep
Sleeping Better With ADHD
Why ADHD and sleep problems often go together, with practical tips.
Read guide - Sleep
Psilocybin And Sleep
What is known about psilocybin and sleep, and why the research is limited.
Read guide
Babies, Children And Teens
Sleep schedules and sleep problems by age.
- Family
Children's Sleep: Newborn To Teen
Sleep needs and common problems from newborn to teen, age by age.
Read guide - Family
Newborn Sleep
What is normal for newborn sleep, feeding and day-night rhythm in the first months.
Read guide - Family
Safe Sleep For Babies
How to set up a safe sleep space and reduce SIDS risk.
Read guide - Family
Baby Sleep Regressions By Age
Which ages are common for sleep regressions and what actually helps.
Read guide - Family
Sleep Training Methods Compared
Cry-based and gradual sleep training methods compared, and how to choose.
Read guide - Family
Baby Sleep Schedule By Age
Naps, wake windows and bedtimes from newborn to 24 months.
Read guide - Family
Teen Sleep Deprivation
Why teens are so tired, how much sleep they need and what helps.
Read guide - Family
When Do Babies Sleep Through The Night?
What studies show at 6 and 12 months, how many wakings are normal, night feeds and safe sleep basics.
Read guide - Family
4 Month Sleep Regression
Why baby sleep changes at 3 to 4 months, signs parents report, whether it lasts and safe ways to cope.
Read guide - Family
School Start Times And Teen Sleep
What the AAP recommends, what Seattle and other studies found, California law and what families can do.
Read guide
Sleep Products
What sleep gadgets can and cannot do.
- Sleep products
The Ideal Sleep Environment
Temperature, light, noise, the bed and air quality: how to set up a room for sleep.
Read guide - Sleep products
Mattress Types Explained
Foam, latex, innerspring, hybrid and airbed, compared by feel, heat, support and lifespan.
Read guide - Sleep products
How To Choose A Pillow
Match pillow loft and fill to your sleep position, shoulders and neck.
Read guide - Sleep products
How Often To Replace A Pillow
When to replace a pillow by fill type, the signs, and how to make it last.
Read guide - Sleep products
Are Sleep Trackers Accurate?
What validation studies show: good at sleep vs wake, weaker on sleep stages.
Read guide - Sleep products
Can An Apple Watch Track Sleep?
How to set it up, what the sleep score counts and what studies say about accuracy and stages.
Read guide - Sleep products
Do Smart Pillows Work?
What smart pillows can and cannot do, from sleep tracking to snore nudges.
Read guide
Sleep Guide FAQs
Where do the facts in these guides come from?
Each guide links to its sources, mainly health agencies such as the NHLBI, NINDS and MedlinePlus, sleep organisations and peer-reviewed studies.
Can these guides diagnose a sleep problem?
No. They explain common causes and options. A doctor or sleep specialist is needed to diagnose a sleep disorder.
Which guide should I read first if I cannot sleep?
Start with how to fall asleep fast for techniques, then the insomnia overview and the CBT-I guide, which explain the first-line treatment.
Are there tools to go with the guides?
Yes. Each topic links to matching calculators, and all of them are on the sleep calculators page.
Medical information boundary. These guides are for general education and are not medical advice or a diagnosis. See a doctor about loud snoring with pauses in breathing, falling asleep during the day, or sleep problems that last more than a few weeks.