Previous research has not fully uncovered the link between sleep apnea and depression. Though the link is not fully understood, potential explanations have been proposed, including the possibility that the obstructive respiratory events and sleep fragmentation cause a neurochemical change resulting in depression; or perhaps, depression and sleep apnea share a similar mechanism of neurochemical dysfunction.1 Because the complaints of daytime sleepiness, fatigue, and lack of enthusiasm are common in both diagnoses, there is often the question of misdiagnosis of depression in the presence of sleep apnea. If sleep apnea is present with depressive symptoms, treating the apnea may improve depression. The case of Lissa, a 32-year-old woman seen for a sleep consultation because of fatigue and daytime sleepiness, supports research demonstrating that CPAP therapy for sleep apnea decreases depression.1-4


At Lissa’s initial sleep consultation, she said that her fatigue and daytime sleepiness had been getting worse for more than 5 years. Furthermore, she admitted that she recently found herself taking a nap at a red light and knew she had to do something.

Her medical history was unremarkable with the exception of a diagnosis of depression made approximately 7 years ago during a time of marital difficulties. She described herself then as very unhappy, not able to get enough sleep (not a night person and not a morning person), and eating to feel better. She was prescribed fluoxetine, which helped at first. However, with each bout of depression (for example, she developed post-partum depression after the birth of her child), the medication was less effective. Throughout the years, she had improvements and relapses of the depression but her sleepiness and fatigue continued to get worse. She stated that she eventually blamed her tiredness on being the mother of two small children.

Eventually, she suspected her problems were more than depression. The combination of night sweats, inability to lose weight despite dieting and exercise, and her sleepiness caused her to believe it was hormonal. Her primary care doctor ruled out any endocrine or metabolic disorder and referred her for a sleep consultation.

There was no family history of sleep disorders except her brother’s history of loud snoring. Her social history includes: she is a stay-at-home mother of a 4-year-old and an 18-month-old child, both in good health; exercises 5 days a week, usually in the morning; nonsmoker; consumes one caffeinated beverage a day and two glasses of wine two to three times per week.

Her vital signs were as follows: blood pressure, 120/80; heart rate, 69; and respirations, 12. Her weight was 198 pounds and her height was 64.5 inches. Her complaints included loud snoring, night sweats, morning headaches, nocturia, vivid dreams, bouts of sleep attacks, legs kicking/twitching during the night, decreased memory and concentration, fatigue, and daytime sleepiness. Her Epworth Sleepiness Scale score was 7.

The diagnostic polysomnogram reported she had 28 obstructive apneas and 88 obstructive hypopneas for an AHI of 19.7 per hour with a REM AHI of 52.7. Arterial oxygen saturation dropped to a low of 78% with an average of 95%. No periodic limb movements were recorded. Her sleep efficiency was 92.3%, with 15.5% in stages III and IV and 19.6% in REM. REM latency was 68.5 minutes. A diagnosis of obstructive sleep apnea, hypoxemia, and abbreviated REM latency was given.

She returned for a second night CPAP titration study. CPAP titration was started at 4 cm H2O and increased to 10 cm H2O. At 10 cm H2O, 1 hypopnea was recorded for an AHI of 0.2 per hour. Supine REM sleep was recorded, and the snoring was eliminated. With CPAP at 10 cm H2O, the arterial oxygen saturation never dropped below 91%. CPAP at 10 cm H2O was prescribed.

Two months later, she returned for a follow-up. She was extremely pleased with her progress. She stated that she felt energized, she was no longer irritable with her children, and her daytime sleepiness was resolved. She stated, “I sing in the car with the radio. I had forgotten that I used to do that!” She also stopped her antidepressant.


Criteria for the diagnosis of depression may include the symptoms of insomnia, loss of energy or fatigue, and diminished ability to concentrate.5 These are also common complaints for patients that experience sleep apnea. Depression and sleep apnea can coexist. Aloia et al found mild depression in 23.6% of 93 patients with sleep apnea and moderate to severe depression in 9.7% of the same sample.6 This is higher than the average in the general population, which is estimated at 9.5% by the National Institute of Mental Health.7

J. Douglas Hudson, MD

CPAP therapy is the most widely accepted treatment for OSA. Treating OSA often reduces depressive symptoms. Kawahara et al demonstrated a reduction in depressive symptoms measured by the Zung self-depression scale (SDS) after 8 weeks of nasal CPAP treatment.2 Inclusion criteria for patients to be in the study were an initial AHI greater than 20/h. CPAP titration was performed on 132 patients so that the average AHI was < 5 and a mean SaO2 of 96±2% was achieved. The baseline score on the SDS was 49.2±10.4 in the OSA patients compared to 43.2±7.5 in 38 controls. After CPAP use, the OSA patients’ SDS significantly decreased to 45.1±9.6 (P <0.0005).

Schwartz et al found similar results.1 The study population consisted of 50 patients experiencing moderate to severe OSA as defined by an RDI > 15. Of the 50 patients, 19 (37%) were taking a stable dose of antidepressants. The Beck Depression Inventory (BDI) was used to measure depression, and initially, 25 patients scored 3 or greater with an average of 7.2 ± 2.6 and 11 of those had scores greater than 6 with an average of 9.5±2.3l, indicating moderate symptoms of depression. After 4 to 6 weeks of consistent CPAP use, the scores dropped significantly to 1.8±2.6 and 2.4±3.4, respectively (P < 0.0001 and 0.0003).

Cherie Simpson, RN, CNS

There are two considerations for both of these studies. The patient sample with depression experienced mild to moderate symptoms. Furthermore, the studies were done after a brief use of CPAP. The benefits of CPAP for the severely depressed patient and the benefits of long-term use of CPAP in diminishing or eliminating depressive symptoms should be topics of ongoing research.

CPAP therapy benefits patients with mild to moderate depressive symptoms. Therefore, patients who experience sleep complaints should be screened for a mood disorder, and patients who present with depressive symptoms should be screened for a sleep disorder.

John Douglas Hudson, MD, is board certified in neurology and sleep medicine. He is the founder of Sleep Medicine Consultants and serves as a principal investigator for Future Search Trials in Austin, Tex. He is also past president of the Texas Neurological Society. Dr Hudson can be reached at . Cherie Simpson, RN, CNS, is a nursing doctoral student at the University of Texas at Austin School of Nursing and practices in adult health. She can be reached at .


  1. Schwartz DJ, Kohler WC, Kartinos G. Symptoms of depression in individuals with obstructive sleep apnea may be amenable to treatment with continuous positive airway pressure. Chest. 2005;128:1304-1309.
  2. Kawahara S, Akashiba T, Akahoshi T, Horie T. Nasal CPAP improves the quality of life and lessens the depressive symptoms in patients with obstructive sleep apnea syndrome. Intern Med. 2005;44:422-427.
  3. Sanchez AI, Buela-Casal G, Bermudez MP, Casas-Maldonado F. The effects of continuous positive airway pressure treatment on anxiety and depression levels in apnea patients. Psychiatry Clin Neurosci. 2001;55:641-646.
  4. Means MK, Lichstein KL, Edinger JD, et al. Changes in depressive symptoms after continuous positive airway pressure treatment for obstructive sleep apneas. Sleep Breath. 2003;1:31-42.
  5. Diagnostic and Statistical Manual of Mental Disorders. 4th ed. Washington, DC: American Psychiatric Association; 1994.
  6. Aloia MS, Arnedt JT, Smith L, Skrekas J, Stanchina M, Millman RP. Examining the construct of depression in obstructive sleep apnea syndrome. Sleep Med. 2005;6:115-121.
  7. Strock M. Depression. Bethesda, Md: National Institute of Mental Health; 2002. Pub 02-3561.