The stages of sleep are the repeating phases the brain moves through each night: three stages of non-REM sleep, called N1, N2 and N3, and then REM sleep. I'm no doctor, so I go by the Canadian Sleep Society, which puts one full round at about 90 minutes. HealthLink BC says the cycle repeats 4 to 6 times in a typical night. Deep N3 sleep piles up early, and REM stretches out toward morning, the society adds.
I'm Michael Ruhr, co-owner of Merit Home Furniture, which has four stores on Vancouver Island. I work the floor in Duncan and sell mattresses and bed frames, not medicine. Every health fact here comes from a named source, such as HealthLink BC, the Canadian Sleep Society, Island Health or a peer-reviewed journal.
What are the 4 stages of sleep?
The 4 stages of sleep are N1, N2, N3 and REM. The US National Institute of Neurological Disorders and Stroke (NINDS) describes two basic types of sleep, REM and non-REM, with three stages inside non-REM.
| Stage | What happens, per NINDS and the Canadian Sleep Society |
|---|---|
| N1, falling asleep | The changeover from waking. Heartbeat, breathing and eye movements slow, and muscles relax with the odd twitch. It usually lasts several minutes. |
| N2, light sleep | Breathing and heart rate slow further, body temperature drops and the eyes go still. Brain waves slow, with brief bursts of activity. The Canadian Sleep Society says more than half of the night is spent here. |
| N3, deep sleep | Also called slow wave sleep, because the brain waves are slow and large. Heartbeat and breathing reach their lowest, and the sleeper is hard to wake. |
| REM, dreaming sleep | The eyes dart behind closed lids, breathing turns irregular, and heart rate rises near waking levels. Arm and leg muscles go limp for a while. NINDS says the first REM comes about 90 minutes after falling asleep. |
The Canadian Sleep Society's Normal Sleep brochure, by Brock University psychologist Kimberly Cote, says healthy young adults fall asleep in 10 to 20 minutes. It adds that several brief awakenings are part of a normal night.
Stages of sleep explained: why some sources say 4 and others 5
Older charts list five stages of sleep and newer ones list four, because the scoring rules changed. From 1968, sleep labs followed the manual of Rechtschaffen and Kales, which split non-REM sleep into stages 1 to 4. Add REM and you get five.
In 2007 the American Academy of Sleep Medicine (AASM) brought in new rules that merged stages 3 and 4, both slow wave sleep, into one stage called N3. A 2009 study in the journal Sleep, by D. Moser of the Medical University of Vienna and colleagues, rescored recordings from 72 people aged 21 to 86 both ways. Under the AASM rules, stage 2 came out about 20 minutes shorter, and N1 and deep sleep roughly 10 minutes longer.
The stages of sleep cycle through the night
The stages of sleep cycle from light non-REM sleep down into deep sleep and on to REM, then begin again. StatPearls, a peer-reviewed medical reference by Aakash Patel and colleagues, puts the average cycle at 90 minutes. HealthLink BC says non-REM and REM alternate 4 to 6 times a night, and that a change in that cycle can make it hard to sleep soundly.
The mix shifts as the night wears on. NINDS says deep sleep comes in longer periods in the first half of the night. The Canadian Sleep Society says the first REM period usually lasts less than 10 minutes, while the last can run more than an hour. So most REM falls in the early morning. Waking out of deep sleep is also why a nap that runs too long can leave you groggy.
Brain waves are how a sleep lab tells the stages apart. NINDS says they slow in N1, carry brief bursts in N2 and slow further in N3, while REM activity looks closer to waking.
What stages of sleep do you dream in?
Dreams can come in any stage, but the vivid ones cluster in REM. NINDS says people spend about two hours a night dreaming, remembered or not, and that dreams are usually most vivid in REM.
How the stages of sleep change with age
A 2004 meta-analysis in the journal Sleep, by M.M. Ohayon of Stanford and colleagues, pooled 65 studies covering 3,577 healthy people aged 5 to 102. In adults, deep sleep and REM took up a smaller share of the night with age, and N1 and N2 a larger one. After 60, only sleep efficiency, the share of time in bed spent asleep, kept falling measurably.
| Age | Sleep at that age, per the source |
|---|---|
| Babies | 16 to 18 hours a day at first (NINDS) |
| School-age children and teens | About 9.5 hours a night (NINDS); teens lean toward later bedtimes (Canadian Sleep Society) |
| Adults | Most need 7 to 9 hours (NINDS); one main sleep, typically 7.5 to 8 hours (Canadian Sleep Society) |
| Later life | About 6 hours on average, less deep sleep, more wakings and earlier hours (Canadian Sleep Society) |
HealthLink BC adds that older adults spend less time in the most restful stages and find it harder to adjust to new sleeping conditions, a different bed among them. It also says these normal changes don't mean the sleep is enough, and suggests a talk with a doctor about ongoing trouble.
Stages of sleep and REM sleep: what missing them may cost
NINDS ties deep sleep to feeling refreshed in the morning. It says memory consolidation most likely needs both non-REM and REM sleep, which stops short of calling it proven. None of these sources sets out fixed stages of sleep deprivation.
The Canadian Sleep Society says a single short night can lower alertness and mood, slow reactions and weaken attention and memory. Over weeks those effects build, and it links long-term short sleep with weight gain, diabetes and heart disease. On little or no sleep, HealthLink BC says not to drive or use machinery while drowsy. NINDS adds that the sleep drive builds with each waking hour, so the following sleep runs longer and deeper.
What is REM sleep behaviour disorder?
REM sleep behaviour disorder, or RBD, is when the normal muscle slack of REM goes missing and a sleeper acts out dreams, sometimes with injury. That's how a 2018 review in Nature Reviews Disease Primers, by Yves Dauvilliers and colleagues, describes it. A firm diagnosis needs a history of dream enactment plus video polysomnography, an overnight sleep study filmed on camera. A bed partner who sees it has good reason to raise it with a doctor.
What a sleep study is like in BC, and how referral works
A sleep study, or polysomnogram, records the stages of sleep and what the body does in each. HealthLink BC says small pads called electrodes go on the head and body with a little glue and tape. Belts around the chest track breathing, and a finger or earlobe clip reads blood oxygen.
- Before. HealthLink BC says patients may keep a sleep diary, skip naps on test day and avoid afternoon caffeine. Tell the doctor about every medicine.
- The night. Lab studies usually run from 10 p.m. to 6 a.m. in a private room, with a technician watching from another room. Most take at least 6 hours.
- After. It isn't painful, though the glue can leave skin itchy. Results go to the doctor, who decides on treatment or more tests.
On the Island, Island Health runs the public sleep lab for adults, focused mainly on obstructive sleep apnea. Its Cowichan District Hospital page, for the Duncan area, lists overnight oximetry at home, done through Royal Jubilee, Cowichan District or Nanaimo Regional General Hospital. A Level 3 home test and a full Level 1 polysomnogram go only through Royal Jubilee in Victoria. Only a respirologist, a lung and breathing specialist, can order those two.
HealthLink BC's listing for the lab says a referral from a family physician or specialist is required. Island Health wants home test equipment back by noon the day after the test, with no exceptions.
Who are the sleep experts?
On the Island, a respirologist orders the full overnight study and a technician runs the night. The Canadian Sleep Society, a national group backing sleep research, clinical care and education, publishes patient brochures by researchers such as Cote. Because a referral is needed, the first stop is a family doctor. Non-sleep deep rest, or NSDR, a label for guided lying-down relaxation, isn't a sleep stage, and none of these health sources defines it.
A bedroom set up for every stage of sleep
HealthLink BC's advice on the room is to keep the bedroom quiet, dark and cool, with curtains or blinds for light and white noise for sound. How cool is cool enough is set out in the bedroom temperatures sleep sources give. Some people add a scent as well, such as lavender, one of the essential oils studied for sleep. It also suggests a comfortable pillow and mattress, and a bed big enough to stretch out in. That last part is where a furniture store comes in, though no bed changes how the stages of sleep are scored.
As of November 1, 2026, Merit lists 20 mattresses for our Duncan store: 10 from Restonic, 8 from Restwell and 2 from Natura. The guide to matching a mattress to the way you sleep works through position, body weight and firmness.
Health Guard's Cool Ice line is listed at Merit's Duncan store: the Cool Ice Pillow at $109.00 and the Cool Ice mattress protector at $189.00 to $249.00, before applicable taxes. Cool Ice is the maker's name, not a sleep claim. Merit's guide for people who sleep hot puts bedroom air first, and choosing a pillow by sleep position covers loft.
Pillows and protectors aren't shipped; they're picked up free at Merit Duncan or added to a mattress delivery booked through Duncan, $150 across the Island with setup. NINDS suggests not using phones or screens in the bedroom, and a nightstand with a drawer puts one out of sight overnight. A phone set to change its own time is worth checking in the fall. BC has dropped the daylight saving time switch, and its clocks stay put all year. Setting a nightstand level with the mattress top keeps the lamp within easy reach.
When sleep trouble needs a doctor, 8-1-1 or 9-1-1
A phone or watch stage chart is a rough guide; NINDS describes app and wearable tracking as informal. HealthLink BC's sleep pages point to a doctor for:
- Daytime sleepiness that gets in the way of normal life.
- Sleep problems that come more often or get worse despite home care.
- Signs it links to sleep apnea: loud snoring, pauses in breathing, choking spells at night, heavy daytime sleepiness and waking unrefreshed.
- Sleeplessness from great pain, or frequent anxiety or nightmares at night.
- Acting out dreams, which the RBD review says needs a sleep study to confirm.
If sleepless nights come with serious thoughts of suicide, call 9-1-1, or Talk Suicide Canada at 1-833-456-4566, the line HealthLink BC lists. For anything else, 8-1-1 reaches HealthLink BC toll-free, any time, and can connect callers with a health professional. 7-1-1 serves the deaf and hard of hearing. A new mattress is the wrong first fix for any of these.
Where the sleep stage facts come from
- National Institute of Neurological Disorders and Stroke, Brain Basics: Understanding Sleep, checked November 2026.
- Canadian Sleep Society, Normal Sleep patient brochure by Kimberly Cote, PhD, Brock University (rev. 2020, copy hosted by Horizon Health Network), checked November 2026.
- HealthLink BC, Sleep Studies, checked November 2026.
- HealthLink BC, Sleep Problems, Age 12 and Older, checked November 2026.
- HealthLink BC, Coping With Changing Sleep Patterns as You Get Older, checked November 2026.
- HealthLink BC, Sleeping Better, checked November 2026.
- HealthLink BC, Insomnia: Improving Your Sleep, checked November 2026.
- HealthLink BC, HealthLink BC 8-1-1 Services, checked November 2026.
- HealthLink BC, Find Health Services: Island Health Sleep Lab, checked November 2026.
- Island Health, Cowichan District Hospital, Sleep Lab section, checked November 2026.
- StatPearls, Physiology, Sleep Stages, Patel, Reddy, Shumway and Araujo (PubMed 30252388), checked November 2026.
- Sleep, 2009: Moser and colleagues, Sleep classification according to AASM and Rechtschaffen and Kales (PubMed 19238800), checked November 2026.
- Sleep, 2004: Ohayon and colleagues, meta-analysis of sleep parameters from childhood to old age (PubMed 15586779), checked November 2026.
- Nature Reviews Disease Primers, 2018: Dauvilliers and colleagues, REM sleep behaviour disorder (PubMed 30166532), checked November 2026.
- Merit Home Furniture's live mattress, pillow and protector listings and store lists, read November 1, 2026, and the owners' delivery and pickup terms.
Talking beds and pillows over with our Duncan store
You'll find Merit Duncan on Ingram Street, number 107, from 9 to 5 Monday through Saturday. Most beds there are display models, so ring ahead to ask which of our Restwell mattress models or the Restonic mattress range are set up for a lie-down. The store keeps a strict no-pressure policy, so there's no rush to decide. The rest of Merit's Vancouver Island mattress pages cover size, feel and care, and the full mattress list shows which store carries each bed.