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Good Morning.

You can read a sleep study cold. AHI, ODI, and nadir SpO₂; you know exactly what they mean. But here's the number that actually predicts whether your appliance ends up in a nightstand drawer, and it isn't on the report. It's a PHQ-9 you never ordered.

Here's the part we rarely say out loud: the AHI on that referral predicts the disease. It tells you almost nothing about whether the patient will actually use what you make for them. The variable that predicts use, more reliably than severity or anatomy, is one that most sleep dentists never measure.

It's mood.

This is Part 1 of a two-part series. Today: why anxiety and depression belong in your sleep work-up, and how to screen for them in under three minutes. Part 2: exactly what to do with the result, chairside.

Key Takeaways (the 30-second version)

• Chronic stress physiology and disrupted sleep run on the same axis. Insomnia behaves like a 24-hour state of hyperarousal, with measurably elevated cortisol, so a wired-up nervous system is fighting your therapy before the device is even in (Dressle et al., 2022).

• Depression is one of the most robust predictors of treatment non-adherence in all of medicine. Roughly three times the odds, across diabetes, cardiac, and oncology care (DiMatteo et al., 2000).

• That now includes oral appliances. A 2025 study using objective wear sensors found that psychological comorbidity significantly reduced long-term OA adherence, whereas having a partner improved it (Chen et al., 2025).

• Two scores, two different failure modes: anxiety predicts early intolerance; depression predicts late drift.

• A positive screen is a reason to prepare differently, not to withhold therapy.

5-minute read 👇

 Mood is a treatment variable, not a side note

Start with the physiology, because it reframes everything. We tend to think of anxiety and depression as the patient's "other stuff", comorbidities for someone else to manage. But chronic sympathetic activation and sleep sit on the same wire. Insomnia is increasingly understood not as a deficit of sleep drive but as a disorder of hyperarousal: a nervous system that won't power down, with elevated cortisol measurable across the 24-hour cycle (Dressle et al., 2022). A patient who arrives chronically keyed up isn't just anxious about treatment; their baseline state is working against the very thing you're trying to restore.

Now layer on adherence. The single best-replicated finding in the adherence literature is blunt: depressed patients are about three times more likely to be non-adherent to medical treatment, a pattern that holds across nearly every specialty studied (DiMatteo et al., 2000). Nightly oral appliance wear is exactly the kind of self-managed, low-immediate-reward regimen that depression erodes.

For years, we could only infer that this applied to our field. As of 2025, we don't have to. A one-year study tracking objective, sensor-measured appliance use found that patients with depression or anxiety had significantly lower long-term adherence — and, notably, that being married or partnered was a consistent protective factor (Chen et al., 2025). Social support shows up in the data as a lever, not a footnote.

Two scores, two failure modes

Here's the clinical move that makes this usable. Anxiety and depression don't fail your treatment the same way.

Anxiety drives early intolerance — the "I couldn't stand it in my mouth" dropout in the first two weeks. This is the claustrophobia, the sensory hypersensitivity, the brisk gag response. The device never gets a fair trial because the nervous system rejects it on contact.

Depression drives late drift — the patient who tolerates the appliance fine, then quietly stops wearing it over weeks to months as motivation and follow-through erode. Nothing dramatic happens. The wear data just trails off.

One honest caveat, because it changes how you read the result: untreated OSA mimics depression. Fatigue, poor concentration, low mood, and broken sleep are core to both. So, a positive depression screen in an untreated apnea patient may partly reflect the apnea itself. That's not a reason to skip screening; it's the reason the screen is a flag for a conversation and, where indicated, a psychiatric consult, not a diagnosis you make.

And the takeaway is not to screen patients out. It's to screen them in, with a different plan: a gentler device, slower titration, structured desensitization for the anxious patient; tighter follow-up and partner involvement for the depressed one. Same diagnosis, different runway.

CLINICAL CORNER: The 3-Minute Mood Check-In

Add two validated, public-domain instruments to your sleep intake — no permission or licensing required:

• PHQ-9 (depression) — a score of ≥10 carries 88% sensitivity and specificity for major depression (Kroenke et al., 2001). Bands: 5 / 10 / 15 / 20 = mild / moderate / moderately severe / severe.

• GAD-7 (anxiety) — bands at 5 / 10 / 15 for mild / moderate / severe (Spitzer et al., 2006).

Quick-read for the sleep work-up:

One non-negotiable: any non-zero answer on PHQ-9 item 9 (thoughts of self-harm) requires a same-visit risk check by someone competent to assess it before the patient leaves.

Frame it for the patient in terms of comfort, not psychiatry: "Sleep and stress are closely linked, so these few questions help me make sure whatever we build actually works for you."

[Download the patient-ready Sleep & Well-Being Check-In (PHQ-9 + GAD-7) →]

A note on this issue's sponsor: More Than Teeth is sponsored in part by Xlear, a Utah-based company whose xylitol-based saline nasal sprays we use as part of our Tier 1 conservative nasal protocol at Advanced Dental Care. Xylitol's mucosal benefits make it a clinically meaningful upgrade over plain saline for patients dealing with chronic congestion and mouth breathing.

We'll cover product-level recommendations in Issue 2. 

COACH CATHY'S TAKE

 By Cathy Bennett, MS, NBCHWC

Here's something the adherence data quietly confirms: people don't change health behaviors alone. In that 2025 appliance study, patients who kept wearing their device were more likely to have a partner in the picture, and from a coaching standpoint, that's no coincidence. A new nightly habit survives or dies in the bedroom, with the person lying next to you.

When a patient is anxious or low, the appliance isn't really competing with apnea; it's competing with a nervous system that's already overwhelmed. Willpower is the wrong tool. What works is to shrink the ask: wear it for 10 minutes while watching TV, not "all night, perfectly." Tiny, winnable steps build the self-efficacy that motivation can't manufacture on a hard day.

So bring the partner in early, name the mood out loud without making it clinical, and lower the first hurdle until it's almost impossible to trip over. You're not asking for compliance. You're building a habit that a tired, stressed brain can actually keep.

Next Issue — Part 2

We've covered how to predict who will struggle. Next time: what to do about it — the Screen-Score Tailored Adaptation Protocol, the chairside decision tree, and how to build a clean psychiatric co-management referral that physicians actually respond to.

REFERENCES

1. Dressle RJ, Feige B, Spiegelhalder K, et al. HPA axis activity in patients with chronic insomnia: A systematic review and meta-analysis of case–control studies. Sleep Med Rev. 2022;62:101588. https://doi.org/10.1016/j.smrv.2022.101588

2. DiMatteo MR, Lepper HS, Croghan TW. Depression is a risk factor for noncompliance with medical treatment: meta-analysis of the effects of anxiety and depression on patient adherence. Arch Intern Med. 2000;160(14):2101–2107. https://doi.org/10.1001/archinte.160.14.2101

3. Chen Y, Pliska BT, Almeida FR. Objective adherence to oral appliance therapy in patients with obstructive sleep apnea: a one-year longitudinal analysis. Eur J Orthod. 2025;47(4):cjaf037. https://doi.org/10.1093/ejo/cjaf037

4. Kroenke K, Spitzer RL, Williams JB. The PHQ-9: validity of a brief depression severity measure. J Gen Intern Med. 2001;16(9):606–613. https://doi.org/10.1046/j.1525-1497.2001.016009606.x

5. Spitzer RL, Kroenke K, Williams JB, Löwe B. A brief measure for assessing generalized anxiety disorder: the GAD-7. Arch Intern Med. 2006;166(10):1092–1097. https://doi.org/10.1001/archinte.166.10.1092

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Until next week,
Dr. Michael & Cathy Bennett
More Than Teeth | A Mission for Generational Health