---
title: "Nighttime Aligners: Do They Work and Who Should Use Them?"
url: "https://www.newmouth.com/orthodontics/treatment/clear-aligners/nighttime/"
description: "Nighttime aligners move teeth with 10 continuous hours of wear a night. See what the research shows, who they suit, and why SmileSet is our night-only pick."
---

Nighttime aligners are clear aligners you wear for 10 continuous hours while you sleep instead of 20 to 22 hours a day. They exist, they move teeth, and SmileSet sells them for the same price as its all-day plan. We usually suggest daytime wear. The research on night-only schedules is thin, and no study has tested SmileSet’s 10-hour protocol. If night-only is the plan you will actually follow and your case is mild, SmileSet is our pick.

## Key Takeaways

-   Nighttime aligners are worn for 10 continuous hours a night. All-day aligners are worn 20 to 22 hours a day, the schedule the American Association of Orthodontists recommends.
-   Research on night-only wear is limited. One small 12-hour study found similar movement accuracy. The one trial built to compare 10 to 12 hours with 20 to 22 hours ended early.
-   We usually suggest daytime wear. Night-only wear suits mild cases and takes longer.
-   SmileSet offers nighttime aligners for $1,295 (list $1,795, depending on when you buy) and is our pick if you want night-only.

## What Are Nighttime Aligners?

Nighttime aligners are [clear aligner](/orthodontics/treatment/clear-aligners/) trays designed to move teeth while you sleep. SmileSet’s version calls for 10 continuous hours a night, with each tray worn three weeks instead of two1. The trays, the dentist review, and the number of aligners match the all-day plan. Only the wear schedule changes.

Continuous is the important word. Ten hours in a row overnight is what the brands prescribe and what the one direct trial set out to test2. Ten hours scattered across a day has not been studied.

![A woman's hand putting a clear nighttime aligner into a blue case](/_astro/cropped-shot-of-a-womans-hand-putting-transparent-night-time-aligner-nm-1197.VAhR1nDf_ghlr2.webp)

A nighttime aligner is not a retainer. An aligner has tooth movement built into it, while a retainer holds teeth where they already are once treatment ends3. If your teeth are straight and you want to keep them that way, you want an [online retainer](/orthodontics/treatment/retainers/online/).

## Do Nighttime Aligners Work?

Teeth move under reduced-wear schedules, but the evidence is small and does not show that 10 hours equals 22. The American Association of Orthodontists tells patients to wear aligners 20 to 22 hours a day or as their orthodontist prescribes4. That schedule dates back to the earliest Invisalign protocols. It is a clinical convention, not a threshold anyone confirmed in a dose-finding trial.

Here is what has been studied. A 2026 retrospective study of 40 adults compared a 3D-printed aligner worn 12 hours a night with a thermoformed aligner worn 22 hours a day. Movement accuracy was similar, 64% versus 65%5. The study was small, used a product SmileSet does not sell, and measured accuracy rather than long-term gum or root health.

The one trial designed to answer the 10-hour question directly was sponsored by Dentsply Sirona, the company behind Byte. It planned to compare 10 to 12 continuous hours with 20 to 22 hours, then enrolled seven people and was terminated in 20252. So the honest summary is limited evidence: not no evidence, and not proof of equivalence either.

## Nighttime vs. All-Day Aligners

Nighttime trays are worn 10 hours a night for six to nine months on SmileSet’s estimate; all-day trays are worn 20 to 22 hours for four to six. The other differences are tray cadence and how much evidence stands behind each schedule.

|  | All-Day Aligners | Nighttime Aligners |
| --- | --- | --- |
| Wear time | 20 to 22 hours a day | 10 continuous hours a night |
| Tray change | Every 2 weeks | Every 3 weeks |
| Treatment time (SmileSet’s estimate) | 4 to 6 months | 6 to 9 months |
| Evidence | Standard protocol, AAO-recommended | Limited, no study of a 10-hour protocol |
| Best for | Mild to moderate cases | Mild cases |
| SmileSet price | $1,295 (list $1,795) | $1,295 (list $1,795) |

SmileSet figures as of September 2, 20261.

Why is nighttime slower? Aligners move teeth by straining the ligament and bone around each tooth while they are in. Current biology does not set a minimum daily hour count6. The practical problem, as one orthodontist explains it, is that a tooth moved overnight drifts partway back during 14 hours out of the tray.

Each tray does less work, and later trays sometimes stop seating on a tooth that has not caught up. Nobody has measured how much longer that makes treatment. SmileSet’s six-to-nine-month figure is the company’s estimate, not a study result.

## Who Should Consider Night-Only Wear?

Night-only wear is for mild cases: a little crowding or spacing, no bite correction, and healthy gums. The studies that have tested reduced wear picked simple, non-extraction cases and left out bite correction, extractions, and cases needing attachments2. No professional body has published a candidacy rule for nighttime aligners, so treat “mild” as a conservative screen rather than a proven cutoff.

The other qualification is honesty about your day. If wearing aligners during the day will be hard, talk it through with your dentist before choosing a plan. Teeth that look only slightly crowded don’t necessarily make you a good fit for nighttime wear. Either way, a licensed dentist reviews your impressions, photos, and treatment plan before anything ships. That review is remote and does not include X-rays or a gum exam, so have your own dentist confirm your gums and bone are healthy before you order.

## When We Wouldn’t Do Night-Only

Night-only wear is the wrong choice in four situations. In each one, choose the all-day plan or see an orthodontist:

-   **Your case is more than mild.** Bite correction, rotated teeth, or any mention of attachments, IPR, or extractions. SmileSet’s own consent form says difficult cases may need traditional braces7.
-   **Your gums are not healthy.** Moving teeth over untreated gum disease is a risk on any schedule. Get an exam and cleaning first.
-   **You sleep in short stretches.** Shift workers and new parents rarely get 10 continuous hours, and split hours have not been studied.
-   **You want the fastest result.** All-day wear is the established protocol, and on SmileSet’s own estimates it finishes two to three months sooner.

If your case is complex, an in-office option like [Invisalign](/orthodontics/treatment/clear-aligners/invisalign-review/) gives a clinician the chance to adjust as you go.

## What Are the Risks of Nighttime Aligners?

The risks of night-only wear are the risks of clear aligners generally, plus a higher chance that treatment stalls. Clear aligner treatment has recognized side effects: soreness with each new tray, root resorption (shortening of the root tips), and gum changes8. A 2024 review of CBCT scans found the root shortening after aligner treatment was small9. None of that research isolates night-only wear as a separate risk factor.

You will read that intermittent force damages roots. The human evidence does not show that. One study that applied force in 28-days-on, 7-days-off cycles found less root resorption, along with less movement, than continuous force10. A separate experiment found “jiggling” forces no more damaging than steady force of the same strength11.

Neither study mimics a 10-on, 14-off aligner day, so they do not prove night wear is safe. They do mean the claim that night aligners cause root damage has no direct support. Root resorption is linked to force and to time in treatment, and night-only plans run longer, so nobody has checked whether that longer timeline matters.

The practical risk is tracking. With less wear, a tray sometimes stops fitting a tooth that has not reached its planned position, and every later tray fits worse. If a tray will not seat, do not force it and do not move on to the next one. Send check-in photos and ask the dentist whether you need a refinement.

Some orthodontists will not recommend night-only wear at all, and they say plainly that this is opinion, because the studies do not exist yet. One who has treated night-only patients reports more soreness complaints than on standard schedules. We think that is a fair position for anything beyond a mild case.

## SmileSet Nighttime Aligners: Our Pick for Night-Only Wear

SmileSet nighttime aligners cost $1,295 (list $1,795, depending on when you buy), the same as its all-day plan1. The impression kit is included. You wear each tray 10 continuous hours a night for three weeks, and SmileSet estimates six to nine months of treatment. A licensed dentist reviews your impressions and treatment plan, and two virtual consultations are included.

SmileSet says its nighttime plan works as well as all-day wear, just more slowly.1 The research we reviewed doesn’t confirm that promise. In [one small Invisalign study](https://pubmed.ncbi.nlm.nih.gov/41372110/) of adults with very mild crowding, both wear schedules helped, but wearing the trays for 22 hours a day straightened the lower teeth more than wearing them for 12. That doesn’t tell us whether SmileSet’s 10-hour plan works as well as its all-day option.

That gap is why daytime wear is the usual suggestion here. For night-only, SmileSet is the pick because the price, the trays, and the dentist oversight match the all-day plan. SmileSet offers the same number of consultations with both plans. That doesn’t mean you can expect the same results from fewer hours of wear.

The nighttime aligners we tested are similar in quality to other nighttime aligners we’ve tried, and taking the impressions felt like other at-home kits. Our full [SmileSet review](/orthodontics/treatment/clear-aligners/smileset/) covers refunds, refinements, and what former [SmileDirectClub](/orthodontics/treatment/clear-aligners/smiledirectclub/) customers should know.

## Frequently Asked Questions

### Does Invisalign offer nighttime aligners?

No. Invisalign is prescribed at 20 to 22 hours a day. An individual orthodontist can adjust wear time for a specific patient, but there is no Invisalign night-only product. [At-home brands](/orthodontics/treatment/clear-aligners/at-home-aligners-safety/) package the reduced schedule as a product; in-office providers prescribe it case by case.

### How much do nighttime aligners cost?

SmileSet charges $1,295 (list $1,795, depending on when you buy), the same as its all-day plan. ALIGNERCO’s NightOnly plan was $925 as of September 2, 2026. Nighttime plans are not consistently more expensive than all-day plans, so compare the plan you would actually wear.