Nighttime Aligners: Do They Work and Who Should Use Them?

Nighttime aligners are clear aligners you wear for 10 continuous hours while you sleep instead of 20 to 22 hours a day. SmileSet sells them for the same price as its all-day plan. We usually suggest daytime wear, because the research on night-only schedules is limited and no published study has tested SmileSet’s 10-hour protocol. Whether night-only wear suits your teeth is a decision for the dentist or orthodontist who examines you. If they agree, and night-only is the plan you will actually follow, 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. In a randomized trial of 50 adults with mild crowding, 22 hours a day corrected the lower teeth more than 12 hours. A small retrospective study of a different product found similar movement accuracy at 12 hours. 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 takes longer, and whether it suits you is your dentist’s call after an exam.
• SmileSet offers nighttime aligners for $1,395 (list $1,895, depending on when you buy) and is our pick if your dentist approves night-only wear.

What Are Nighttime Aligners?

Nighttime aligners are clear aligner 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 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.

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, compared two different products, used neither of SmileSet’s, and measured accuracy rather than long-term gum or root health.

A randomized trial gives the clearest comparison so far. It assigned 50 adults with mild crowding to Invisalign worn either 12 or 22 hours a day. Both groups improved, but the lower teeth lined up better with 22 hours, and the upper teeth showed no significant difference⁶. It did not test SmileSet or a 10-hour schedule.

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.

SmileSet figures as of October 9, 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 count⁷. The practical concern is that a tooth moved overnight may drift 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?

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 whether night-only wear suits you is a judgment for the dentist or orthodontist who examines you. SmileSet’s own consent form says its prescribing dentist may prescribe 22-hour aligners even if you asked for nighttime ones⁸.

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. The first two need an in-person exam before any aligner plan, remote or not:

• Your dentist finds more than mild crowding or spacing. Bite correction, rotated teeth, or any mention of attachments, IPR, or extractions. SmileSet’s own consent form says difficult cases may need traditional braces⁸. See an orthodontist in person.
• Your gums are not healthy. Moving teeth over untreated gum disease is a risk on any schedule. Get the gum problem treated first.
• You sleep in short stretches. Shift workers and new parents rarely get 10 continuous hours, and split hours have not been studied. Ask your dentist which schedule fits.
• 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 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 changes⁹. A 2024 review of CBCT scans found the root shortening after aligner treatment was small¹⁰. None of that research isolates night-only wear as a separate risk factor.

No study has tested whether a 10-hours-on, 14-hours-off aligner day changes the risk of root resorption, in either direction. Root resorption is linked to force and to time in treatment, and night-only plans run longer, so that question remains open.

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.

SmileSet Nighttime Aligners: Our Pick for Night-Only Wear

SmileSet nighttime aligners cost $1,395 (list $1,895, 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 the randomized Invisalign trial described above, both wear schedules helped, but wearing the trays for 22 hours a day straightened the lower teeth more than wearing them for 12⁶. 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. If your dentist approves night-only wear, 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.

Our full SmileSet review covers refunds, refinements, and what former 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 package the reduced schedule as a product; in-office providers prescribe it case by case.

How much do nighttime aligners cost?

SmileSet charges $1,395 (list $1,895, depending on when you buy), the same as its all-day plan. ALIGNERCO’s NightOnly plan was $925 as of October 9, 2026. Nighttime plans are not consistently more expensive than all-day plans, so compare the plan you would actually wear.