What is a heavy sleeper?

What does heavy sleeper mean?

Sleep researchers talk about your arousal threshold: how strong a sound or touch has to be to wake you. Light sleepers have a low threshold, and heavy sleepers have a high one. That's why one person wakes at a creaky floorboard while another sleeps through a thunderstorm.

There's no official cutoff for being a heavy sleeper, and the Sleep Foundation says researchers still don't know exactly what makes someone one. People also use "deep sleeper" to mean the same thing, though deep sleep is also a stage of sleep everyone goes through.

Why some people are harder to wake

Most of this research is from small lab studies, usually using tones or smoke alarms rather than phone alarms. So treat these as likely factors, not proven causes.

• Deep sleep. You're harder to wake from deep sleep, and most of it happens in the first half of the night.
• Sleep spindles. These are short bursts of brain activity during sleep. In one study of 12 adults, people with more of them tolerated noise better, which may help explain why some sleepers aren't disturbed.
• Age. Children and teens can be very hard to wake, and people tend to wake more easily as they get older.
• Missed sleep. When you're short on sleep, your body catches up with extra deep sleep, and you can be harder to wake.
• Alcohol. It adds deep sleep early in the night and disrupts the second half.
• Some medicines. Sedating medicines can make you harder to wake or sleepier. Talk to your prescriber, and don't stop a medicine on your own.
• Your genes. Researchers think genetics may play a part, but there's no clear answer yet.

Why you turn off alarms and don't remember

Being hard to wake is only half of it. Many heavy sleepers do wake up, just not properly. Sleep inertia is the groggy state right after waking, and it usually lasts 15 to 60 minutes. While you're in it, you can stop an alarm and fall straight back to sleep.

That's the likely reason people turn off alarms with no memory of it, although it hasn't been studied much directly. It's also why a louder alarm often doesn't fix things: if you can stop it without really waking up, volume doesn't matter much.

How much sleep do you need?

Sleep experts recommend 7 or more hours a night for adults, and 8 to 10 for teens aged 13 to 18. If you're regularly getting less, fix that first. You may not be a heavy sleeper so much as a tired one.

When to see a doctor

Being a heavy sleeper is usually nothing to worry about. It's worth talking to a doctor if:

• You sleep enough but still feel very tired during the day, for more than a few weeks.
• Oversleeping is causing problems at work, school or with appointments.
• You snore loudly, gasp or choke in your sleep, or someone notices your breathing stop. These can be signs of sleep apnea.
• You find it very hard to wake up and feel confused for a long time afterwards. Hypersomnia can cause this.
• Your low mood and sleep have changed together. Depression can affect both.

Only a doctor can tell you what's going on, and this page can't. It's general information, not medical advice.

How to wake up if you're a heavy sleeper

• Get enough sleep and keep the same wake-up time every day.
• Put your alarm across the room, so you have to stand up.
• Let in bright light as soon as you're up.
• Use an alarm you can't stop from bed.

There's more detail in how to wake up to an alarm as a heavy sleeper and why you sleep through your alarm. To choose a sound, see the best alarm tones for heavy sleepers.

We built WakeUpBroo for exactly this. It has no snooze and no dismiss button, and you pick how each alarm stops: a code from your computer, a random item to scan, or three words to remember. See how it compares in our guide to alarm apps for heavy sleepers.

Sources

• Sleep Foundation: light sleepers and heavy sleepers
• Sleep Foundation: stages of sleep
• Sleep Foundation: sleep inertia
• Dang-Vu et al., 2010: sleep spindles and noise
• Busby et al., 1994: waking thresholds and age
• Ebrahim et al., 2013: alcohol and sleep
• Hilditch and McHill, 2019: sleep inertia review
• AASM and SRS: recommended sleep for adults
• AASM: recommended sleep for teens
• Cleveland Clinic: hypersomnia
• Cleveland Clinic: oversleeping
• NHS: sleep apnoea
• NHS: why am I tired all the time?