Does mouth tape improve deep sleep or REM?

Nobody has shown yet that mouth tape changes deep sleep or REM sleep in everyday sleepers. The best-known study measured snoring, breathing and oxygen, not sleep stages. One older study did find more REM sleep with tape, but only in people using a nasal breathing machine at night. So if your tracker shows a jump in deep sleep after you start taping, it might be real, but neither the research nor the tracker can confirm it yet.

That isn't bad news for mouth tape. It just means the evidence is strongest for the things researchers actually measured, and it's worth knowing which numbers on your sleep app rest on solid ground.

What are deep sleep and REM sleep?

Deep sleep and REM sleep are two of the stages your brain cycles through each night. The NHLBI describes deep sleep as stage 3 of non-REM sleep, also called slow-wave sleep after a brain wave pattern seen in sleep studies. REM sleep is the active, dreaming stage, when brain activity looks similar to being awake.

According to the NHLBI, you move through a full cycle of non-REM and REM sleep every 80 to 100 minutes, usually four to six times a night. You tend to get more deep sleep early in the night and more REM sleep later on. Deep sleep also falls with age: the NHLBI says slow-wave sleep keeps decreasing through adulthood, and some older people may have none at all.

One detail matters for everything below. The NHLBI notes that sleep studies classify stages using sensors that record eye movements and brain activity. Without those signals, a device is estimating your stages, not measuring them. Our guide to sleep stages explained covers each stage in more depth.

Does mouth tape improve deep sleep?

Mouth tape hasn't been shown to improve deep sleep, because almost no one has measured it. No published study has compared deep sleep with and without mouth tape in ordinary adults using a lab sleep study. The one taping study with deep sleep data found a rise that wasn't statistically significant, in a very specific group of patients.

That study, published in 1999 in the European Respiratory Journal, involved 9 people on long-term nasal bilevel ventilation, a breathing machine that pushes air through a nose mask. All of them had air leaking out through their mouths. Each slept two nights in random order, one with the mouth taped. Deep sleep went from 13.1% to 19.5% of sleep time with tape, but the authors describe the change as inconsistent, and it didn't reach statistical significance.

The 2025 systematic review in PLOS One, which pulled together 10 studies and 213 patients, didn't find any other mouth taping study that reported deep sleep. It also rated every study it included as poor quality. Our mouth taping research tracker lists every published trial if you want to check for yourself.

Does mouth tape increase REM sleep?

Mouth tape increased REM sleep in one small study, and only in people using a breathing machine. In the 1999 study above, REM sleep rose from 12.9% to 21.1% of sleep time on the taped night. Arousals, the brief awakenings that break up sleep, fell in every patient, from an average of 35.0 to 13.9 an hour.

Those are big changes, and they make sense for that group. With the mouth taped, air leaking out of the mouth fell from 0.35 to 0.06 liters a second, so the machine could do its job. Sleep latency, the time it took to fall asleep, and sleep efficiency didn't change.

The catch is that these were 9 people on a nasal breathing machine with a known leak problem, not healthy sleepers or people who simply snore. The PLOS One review found only one other study that looked at REM sleep, and it tested a chin strap rather than tape. If you use CPAP with a nasal mask and wake up with a dry mouth, our page on mouth tape and CPAP covers that situation, and it's one to plan with your sleep doctor.

What did the 2022 Healthcare study measure?

The 2022 study in Healthcare measured snoring, breathing events and oxygen levels, not sleep stages. Researchers in Taiwan gave 20 mouth breathers with mild sleep apnea a home sleep test, then a second one a week later while they slept with their mouths taped. The paper reports no deep sleep, REM or other stage data.

What it did report was encouraging. The median snoring index fell from 303.8 to 121.1 events an hour, a drop of 47%, and 13 of the 20 people cut their snoring by at least half. The apnea-hypopnea index, a count of breathing pauses and shallow breaths an hour, fell from 8.3 to 4.7. Our guide to what AHI means explains that number. The study was small, had no control group, and the authors note a home test may underestimate sleep apnea. These are research results, and mouth tape isn't a treatment for sleep apnea.

A 2015 pilot study of a porous patch that holds the lips closed did use a full lab sleep study, in 30 people with mild sleep apnea who slept with their mouths open. Its summary reports less snoring, a lower AHI and less daytime sleepiness, but no sleep stage results.

What has research measured so far?

Here's how the main studies line up on sleep stages.

So the honest summary is that the sleep-stage question is open. Less snoring and fewer mouth-breathing problems are what research has measured most consistently.

Can your sleep tracker measure deep sleep?

A consumer sleep tracker can estimate deep sleep, but it can't measure it the way a lab sleep study does. Watches and rings don't record brain activity the way a sleep lab does, and studies that compare them with a sleep lab find their stage numbers are the weakest part of the report.

A 2021 study in Sleep tested seven consumer devices against a lab sleep study in 34 healthy young adults. The devices were good at detecting sleep but their sleep stage results were inconsistent, and most did worse on nights with disrupted sleep. A 2022 study of 49 adults being checked for sleep disorders found two sports watches overestimated light sleep and underestimated deep sleep, one of them significantly, with an average error of up to about 65 minutes. A 2024 review of reviews found wearables also tend to overestimate total sleep time, with errors typically above 10%.

That doesn't make your tracker useless. It means a change of 10 or 15 minutes in deep sleep on one night is well inside the device's margin of error. Our guide to snoring apps and sleep trackers goes deeper on what they can pick up.

Why might your deep sleep look different after taping?

Your deep sleep number can change after you start taping for several reasons, and only some of them involve the tape. A real shift in your sleep is possible. So is ordinary night-to-night variation, a change in when you went to bed, or the tracker simply scoring a quieter, stiller night differently.

A few things to keep in mind when you read the chart:

• Deep sleep naturally clusters early in the night, so going to bed later or waking earlier changes the total.
• Trackers did worse on disrupted nights in the 2021 study, so a restless first night with tape may score oddly.
• Age lowers deep sleep on its own, so comparing your numbers with a friend's tells you little.

The fairest test is to compare yourself with yourself. Keep your bedtime steady, use the same device, and compare a week or two without tape against a week or two with it. Our step-by-step guide to tracking your mouth tape results sets out a simple two-week log.

What should you judge mouth tape on instead?

Judge mouth tape mainly on the things it's most likely to change: snoring, a dry mouth in the morning and whether you wake with your lips together. Those are closer to what the research measured, and they're easier to track honestly than a stage chart.

A snoring app or a bed partner's report gives you a before and after. A simple 1 to 5 score for morning dry mouth works too. If your sleep tracker's averages for deep sleep, REM or wake time move in the same direction across a couple of weeks, that's a nice extra sign. If they don't move at all but you snore less and wake with a wetter mouth, the tape is still doing its job.

Before any of this, make sure you can breathe easily through your nose with your mouth closed. Loud snoring with gasping, choking or pauses in breathing needs a doctor, not tape, and our page on whether mouth taping is safe lists who should skip it. We don't recommend mouth tape for children.

Our pick (paid partner): Titan Bamboo Silk Mouth Tape

If you want to run your own before-and-after, our pick is Titan Bamboo Silk Mouth Tape. We haven't tested or ranked mouth tapes ourselves, and no tape has been shown to change sleep stages; this is our recommendation based on how Titan describes its tape.

Titan says the strip is bamboo silk, which it describes as soft, breathable and moisture-wicking, and that it has no printed logo or ink on the side that touches skin. It comes in one oval size, 76 by 38 mm, worn horizontally across the lips. Titan suggests 20 to 30 minutes of daytime practice before the first night. It says every batch is third-party tested and certified PFAS-free, and its 30-night guarantee refunds you if your sleep isn't better after 30 nights, which lines up well with a two-week tracking test.

Read next

• How to tell if mouth tape is working
• Nasal breathing and sleep quality
• How to start mouth taping: your first week

* This content is for informational and educational purposes only and is not medical advice. It is not intended to diagnose, treat, cure or prevent any disease or health condition. Talk to a qualified healthcare provider about your health.