If you spend eight hours in bed but wake up several times, you can still wake up tired. Broken sleep, which doctors call sleep fragmentation, cuts your sleep into pieces, so you spend less time in the deeper, more restoring stages. Research links it with worse mood, poorer memory and changes in how your body handles sugar. The good news: most causes can be found and treated.
In this article
The short answer
- Short awakenings at night are normal; many are too brief to remember.
- Frequent awakenings reduce deep sleep and leave you less refreshed.
- In a Johns Hopkins study, broken sleep lowered positive mood more than the same amount of shortened, unbroken sleep.
- Common causes: sleep apnea, needing the toilet, pain, alcohol, stress, noise and light.
- Loud snoring, gasping or daytime sleepiness need a doctor’s check.
What fragmented sleep is
Sleep runs in cycles of roughly 90 minutes, moving through light sleep, deep (slow-wave) sleep and REM sleep. Brief awakenings between cycles are a normal part of sleep, and awakenings of less than a few minutes are often forgotten by morning.
Sleep becomes fragmented when you wake, or nearly wake, many times. Each interruption can pull you out of deeper sleep and restart the climb back down. So the hours in bed look fine, but the sleep is lighter and less restoring.
What broken sleep does to you
Mood
In a 2015 Johns Hopkins study (Finan and colleagues, Sleep), 62 healthy adults spent three nights in a sleep lab. One group was woken up several times each night; another went to bed later but slept without interruption, for a similar total amount of sleep. By the second day, positive mood had fallen by 31% in the woken group, compared with 12% in the later-bedtime group. The woken group also had less deep sleep.
Blood sugar
In a small 2010 study in the journal Chest (Stamatakis and Punjabi), healthy adults whose sleep was broken up by sounds for two nights became about 25% less sensitive to insulin, which means their bodies handled sugar less well. These were short lab experiments, but they help explain why poor sleep is linked with type 2 diabetes in large population studies.
Memory
Deep sleep and REM sleep both play a part in turning new learning into lasting memories. When sleep is repeatedly broken, there is less of the deep sleep that this process relies on, which is one reason broken sleep can leave you foggy and forgetful.
Heart health
Population studies link poor, broken sleep with high blood pressure and heart disease. Much of that link runs through sleep apnea, a condition in which breathing stops and starts many times an hour, waking the brain briefly each time. That is one more reason to get frequent waking checked.
Find the cause
| Type | Common causes |
|---|---|
| Medical | Sleep apnea, restless legs, chronic pain, acid reflux, needing the toilet at night, menopause symptoms, some medicines |
| Bedroom | Noise, light, a warm room, an uncomfortable mattress, a snoring partner or a pet on the bed |
| Mind | Stress, anxiety, depression, trauma |
| Habits | Alcohol in the evening, caffeine after midday, late heavy meals, an irregular schedule |
Alcohol deserves a special mention: it helps you fall asleep but disturbs the second half of the night. For more on early-morning waking, read why you keep waking up at 4 AM.
How to sleep more soundly
- Make the bedroom dark, quiet and cool. Blackout curtains or an eye mask, earplugs or a fan or white noise, and a cool room. A 2022 Northwestern University study found that sleeping with moderate room light raised heart rate at night and made the body handle sugar less well the next morning.
- Keep a regular schedule, especially your wake-up time, and get daylight soon after waking.
- Cut alcohol in the evening and caffeine after midday.
- Drink less in the last two hours before bed if you wake up to use the toilet.
- Finish big meals two to three hours before bed.
- Wind down with dim light and no work or bright screens in the last hour.
- If you wake and cannot get back to sleep within about 20 minutes, get up and do something calm in dim light until you feel sleepy.
Try this tonight
Skip the evening drink, stop drinking fluids two hours before bed, and make the room as dark as you can. Note in the morning how many times you remember waking.
Supplements and sleeping pills
Low-dose melatonin, magnesium and glycine have some research behind them for sleep, mostly from small studies with modest effects. Sleeping pills can help in the short term, but some can cause dependence or next-day drowsiness, and none of them treats the cause of broken sleep. Talk to a doctor or pharmacist before you take any of them.
When to see a doctor
- You snore loudly, gasp or choke at night, or someone sees you stop breathing.
- You are very sleepy during the day or nod off without meaning to.
- You wake up with headaches.
- You get up to use the toilet two or more times most nights.
- Broken sleep has lasted more than a few weeks despite the steps above.
Sleep apnea is one of the most common hidden causes of broken sleep, and it is very treatable. If our snore quiz flags warning signs, ask your doctor about a sleep test.
Frequently Asked Questions
How many times is it normal to wake up at night?
Waking briefly once or twice and falling straight back to sleep is common, and it becomes more common with age. It is worth looking into if you wake often, stay awake for long, or feel tired during the day.
Is fragmented sleep the same as insomnia?
Not exactly. Insomnia means trouble falling or staying asleep that you are aware of. Fragmented sleep can also include brief awakenings you do not remember, for example from sleep apnea.
Can I catch up on the weekend?
Extra sleep can reduce some sleep debt, but it does not fix the cause of broken sleep. A regular schedule every day usually works better.
Should I track my sleep with a device?
A tracker can show patterns, but consumer devices are not very accurate at counting awakenings, and watching the numbers makes some people more anxious. How you feel during the day is a good guide.
The bottom line
Sleep quality matters as well as sleep quantity. If you wake often, look for the cause: your bedroom, alcohol, caffeine, the toilet, stress, or a medical problem such as sleep apnea. Fix what you can, and see a doctor if the warning signs above sound familiar.
Sources
- Finan PH, et al. The effects of sleep continuity disruption on positive mood and sleep architecture in healthy adults. Sleep, 2015.
- Stamatakis KA, Punjabi NM. Effects of sleep fragmentation on glucose metabolism in normal subjects. Chest, 2010.
- Mason IC, et al. Light exposure during sleep impairs cardiometabolic function. PNAS, 2022.
This article is general information, not medical advice. See our medical disclaimer.
[…] Both matter. Seven hours of broken sleep will not feel like seven good hours. Read about what broken sleep does to your body. […]