Prevalence of sleep apnea and nocturnal myoclonus in major affective disorders: clinical and polysomnographic findings

Bidirectional relationships of comorbidity with obstructive sleep apnoea

Obstructive sleep apnoea (OSA) is frequently associated with comorbidities that include metabolic, cardiovascular, renal, pulmonary and neuropsychiatric. There is considerable evidence that OSA is an independent risk factor for many of these comorbidities but, more recently, there is evidence that some of these comorbidities may predispose to the development of OSA. Thus, there is growing evidence of a bidirectional relationship between OSA and comorbidity, especially for heart failure, metabolic syndrome and stroke. Potential mechanisms of bidirectional relationships differ in individual comorbidities with fluid retention and redistribution being especially important in heart failure and end-stage renal disease, whereas neural mechanisms may be more important in diabetes mellitus and stroke. The evidence for other comorbidities, such as hypertension and atrial fibrillation, support these being more a consequence of OSA with limited evidence to support a bidirectional relationship. The present review explores the evidence for such bidirectional relationships with a particular perspective on comorbidities that may predispose to OSA. The impact of therapy in bidirectional relationships is also reviewed, which highlights the clinical importance of accurate diagnosis. This aspect is especially true of COPD, where the identification of co-existing OSA has important implications for optimum therapy.

Obstructive sleep apnoea (OSA) is an independent risk factor for comorbidity, especially cardiometabolic. However, some comorbidities may be risk factors for OSA, supporting a bidirectional relationship that may have important implications for treatment.https://bit.ly/3BbJy6V

Obstructive sleep apnea (OSA) and clinical depression-prevalence in a sleep center

BACKGROUND

This study aimed to determine the prevalence of clinical depression as defined by ICD-10 criteria in all patients with obstructive sleep apnea (OSA) referred to a sleep center.

METHODS

Prospective general and sleep evaluations were conducted in 447 consecutive patients referred to our sleep center during the first quarter of 2008. Inclusion criteria were Apnea Hypopnea Index (AHI) > 9, completion of the Beck Depression Inventory (BDI-II) with a score ≥14 and World Health Organization WHO-5 Well-Being Index (WHO-5) ≤ 13. The subsequent psychiatric examination according to ICD-10 criteria was performed by in-house clinical sleep specialists.

RESULTS

A total of 447 patients were surveyed, of whom 322 had an AHI > 9. Out of these, 85 met the combined screening criterion BDI II ≥ 14 and WHO-5 ≤ 13. Eighty-one patients underwent a psychiatric examination by psychiatric sleep specialists. In 21.5 % of the sample, clinical depression was diagnosed. Other complaints existed in 12 % (n = 10); 7 % (n = 6) of patients had a different psychiatric diagnosis.

CONCLUSIONS

The prevalence of clinical depression according to ICD-10 criteria in a selected clinical sample (referred to the sleep center) was 21.5 %. Mood scales tend to overestimate complaints as compared to psychiatric consultation. Interdisciplinary cooperation is recommended for both OSA patients with symptoms of depression and depressed patients with treatment resistance.

Obstructive sleep apnea in psychiatric outpatients. A clinic-based study

Psychiatric diseases and symptoms are common among patients with obstructive sleep apnea (OSA). However, only a few studies have examined OSA in psychiatric patients. At the outpatient clinic of the Uusikaupunki Psychiatric Hospital, Finland, we used a low referral threshold to a diagnostic sleep study. An ambulatory cardiorespiratory polygraphy was performed in 114 of 221 patients. 95 patients were referred by the psychiatric clinic and 19 were examined in other clinical settings. We reviewed the medical files and retrospectively assessed the prevalence of OSA and the effect of gender, age, obesity, hypertension, type 2 diabetes, alcohol abuse, and symptoms suggesting OSA. 58 of the 221 patients (26.2%), 30 of 85 men (35.3%) and 28 of 136 women (20.6%), had OSA as determined by an apnea-hypopnea index (AHI) of 5/h or more. 20 patients (12 men and 8 women) had moderate or severe OSA (AHI ≥ 15/h). 46 patients (including 11 patients with moderate or severe OSA) were identified in the psychiatric clinic. In univariate analysis, a high body mass index, male gender, hypertension, snoring, and a history of witnessed apneas during sleep were associated with the presence of OSA. In multivariate analysis, a history of witnessed apneas did not remain significant. Age, type 2 diabetes, alcohol abuse, excessive daytime sleepiness (EDS), and fatigue did not associate with the presence of OSA. Our findings suggest that in psychiatric outpatients OSA is common but underdiagnosed. Presentation is often atypical, since many patients with OSA do not report witnessed apneas or EDS.

Depressive symptoms and sleep: a population-based polysomnographic study

The goals of the present study were to determine the prevalence of depression in the adult population of Sao Paulo, Brazil and to explore the relationship among sociodemographic, physical and psychological factors, sleep-related symptoms and polysomnography parameters. Participants of a cross-sectional study (N = 1101) were administered questionnaires and submitted to polysomnography. A score > 20 in the Beck Depression Inventory was used to describe depression. Results revealed that the prevalence of depression was 10.9%. Estimates were higher in women and were significantly higher among housewives, non-workers and individuals with lower education and income. A combination of sleep-related symptoms and impaired quality of life was 2.5 times more frequent among depressed than non-depressed. Co-morbid insomnia and anxiety were positively associated to depressive symptomatology. There were no alterations in the polysomnography parameters, in either group. The occurrence of sleep apnea with values on the apnea-hypopnea index ≥ 5 was similar and frequent in both groups (around 30%). The findings suggest that depressive symptoms were associated with low education, low income, severe comorbid symptomatology, and impaired quality of life. Considering the high prevalence of sleep apnea, these results point to potential social and financial burdens associated with the depressive symptomatology and various sleep diagnoses.

REM rebound and CPAP compliance

OBJECTIVE/BACKGROUND

The objective of this study was establish if rapid-eye-movement (REM) rebound on first exposure to continuous positive airway pressure (CPAP) is associated with CPAP compliance. A rebound or drastic increase in REM sleep in response to initial CPAP exposure is associated with improvement in the subjective quality of sleep. We wished to determine if REM rebound was also associated with increased CPAP compliance.

METHODS

Split night polysomnographic studies carried out in a one-and-a-half year period were examined for REM rebound and slow wave sleep (SWS) rebound. Compliance with CPAP according to percentage of days used and percentage of days used for more than 4h was determined at 30, 60, and 120 days and compared between groups with and without REM rebound and then between groups with and without SWS rebound. Multivariate regression models were constructed to determine factors that were associated with increasing CPAP compliance.

RESULTS

CPAP compliance was greater for those with REM rebound than those without REM rebound at all time periods, but significantly so only for total percentage of days used at 30 days (86.7±46.7, 96.7 vs. 56.7 [median±1st quartile, 3rd quartile]±32.5, 90.0; p=0.04) and 60 days (78.3±37.5, 93.4 vs. 50.0±25.0, 80.9; p=0.03). There was no difference in CPAP compliance for SWS rebound and there were no SWS rebound groups. Only the presence of REM rebound was associated with increased compliance with CPAP with neither SWS rebound nor diagnostic AHI being significantly associated with CPAP compliance.

CONCLUSIONS

The presence of REM rebound, but not SWS rebound, on initial CPAP exposure is associated with early CPAP compliance. This increased compliance is not explained by severity of sleep apnea as measured by AHI.

Restless legs syndrome: study of prevalence among medical school faculty members

The aim of this study was to assess the prevalence of idiopathic restless legs syndrome (RLS) and its correlations in a sample of Medical School faculty members. A transversal study was conducted at a Medical School in the south of Brazil included 78 faculty members. The subjects answered to a structured questionnaire specific to RLS diagnosis and the Epworth and the Stanford scales to measure daytime sleepiness. Severity of the disease was also evaluated. The variables were analyzed to statistical significance. RLS was diagnosed in 10.25% of the subjects evaluated and most were women (62.5%). The prevalence of daytime sleepiness was significantly greater among the subjects suffering from RLS (p=0.04). RLS subjects were significantly younger than the group without the syndrome (p=0.02). RLS had a considerable prevalence in the sample studied. Daytime sleepiness and young age showed an important correlation to this syndrome, as other potential factors were not confirmed.

Frequency and predictors of obstructive sleep apnea among individuals with major depressive disorder and insomnia

OBJECTIVE

Disturbances in sleep continuity are common among individuals with major depressive disorder (MDD) and can impact the course of depression and response to treatment. Several studies have examined depressive symptom severity among sleep-disordered patients with obstructive sleep apnea (OSA). In contrast, little is known about OSA in patients with MDD. The goal of this study was to examine the frequency and predictors of OSA in a sample of individuals with comorbid MDD and insomnia.

METHODS

Participants were 51 individuals who enrolled in a treatment study on insomnia and depression, met criteria for MDD and comorbid insomnia, and underwent an overnight polysomnography evaluation. An apnea-hypopnea index >or=15 events per hour was used as a cutoff score for OSA. Regression analyses were conducted to examine clinical and demographic predictors of OSA severity as measured by the apnea-hypopnea index.

RESULTS

The results revealed that 39% of the sample met criteria for OSA. The OSA group had significantly higher body mass index (BMI) scores and a significantly greater proportion of men. Regression analysis revealed that male sex, older age, and higher BMI were significant predictors of OSA severity. Neither depression severity nor insomnia severity was a significant predictor.

CONCLUSIONS

These findings indicate that the frequency of OSA is higher among individuals with comorbid MDD and insomnia than was previously found among people with either MDD or insomnia alone. In addition, previously identified predictors of OSA (male sex, older age, and high BMI) also apply to this population.

Onset of mania after CPAP in a man with obstructive sleep apnea

BACKGROUND

This short report presents the case of a man with chronic anergy and mild depressive symptoms probably due to obstructive sleep apnea (OAS).

METHOD

The patient was treated with continuous positive airway pressure (CPAP).

RESULT

He developed a first manic episode at an atypical age simultaneously with the beginning of treatment.

DISCUSSION

Several possible connections between affective syndromes, OAS, and CPAP treatment are proposed and discussed relating to current literature.

Depression and obstructive sleep apnea in patients with coronary heart disease

OBJECTIVE

Depression is a risk factor for cardiac events in patients with coronary heart disease (CHD). Obstructive sleep apnea/hypopnea syndrome (OSAHS) is frequently comorbid with depression and is also a risk factor for cardiac events. Undetected OSAHS could help explain the increased risk associated with depression.

METHODS

Medically stable patients with CHD and major (MD, n = 53), minor (md, n = 36), or no depression (ND, n = 43) were evaluated for 2 nights in a sleep medicine laboratory.

RESULTS

The prevalence of OSAHS did not differ across groups (MD 66%, md 69%, ND 77%; p > .05). Patients with MD had a significantly greater frequency of apneic episodes, a significantly longer duration of apneas and hyponeas, and more oxygen desaturations per hour than those with md, but there were no differences between MD and ND in frequency of apneic episodes or oxygen desaturations. However, males with MD tended to have more obstructive episodes per hour than did ND males, whereas females with MD had fewer episodes than did ND females. Apnea duration was longer in patients with MD compared with patients with no ND. There was no difference in the mean duration of apnea per hour between the md and ND groups.

CONCLUSIONS

Although OSAHS is not more common in depressed patients with CHD, MD is associated with longer obstructive sleep apneic episodes in both men and women and with a higher frequency of episodes in men.

Sleepiness is not the inverse of alertness: evidence from four sleep disorder patient groups

The constructs "sleepiness" and "alertness" are often assumed to be reciprocal states of consciousness. This distinction is of increasing concern in relation to psychomotor performance tasks such as driving. We developed two separate subjective scales of alertness to complement existing sleepiness scales. Subjective sleepiness and alertness were compared in four groups of sleep-disordered patients. In a 175-patient cohort [25 narcoleptics and 50 each with sleep apnea, insomnia and periodic leg movement disorder (PLMD)], the Epworth Sleepiness Scale (ESS) was used to measure sleepiness while the Toronto Hospital Alertness Test (THAT) and ZOGIM Alertness Scale (ZOGIM-A) were used to measure alertness. Significant differences existed for sleepiness scores, with narcoleptics scoring highest on the ESS, followed by sleep apnea, with similar ESS scores for insomnia and PLMD. By contrast, alertness scores on both the THAT and ZOGIM-A did not differ significantly between the four groups. Sleepiness scores show a correlation of close to nil to alertness scores for the combined sleep disorder patient cohort, with the exception of insomnia patients, where a modest but significant inverse relationship was noted between sleepiness and alertness. Subjective states of impaired alertness and excessive sleepiness are independent constructs in the evaluation of sleep-disordered patients. The specific primary sleep disorder diagnosis may play a relevant role in mitigating this interrelationship.

Depression and Obstructive Sleep Apnea (OSA)

For over two decades clinical studies have been conducted which suggest the existence of a relationship between depression and Obstructive Sleep Apnea (OSA). Recently, Ohayon underscored the evidence for a link between these two disorders in the general population, showing that 800 out of 100,000 individuals had both, a breathing-related sleep disorder and a major depressive disorder, with up to 20% of the subjects presenting with one of these disorders also having the other. In some populations, depending on age, gender and other demographic and health characteristics, the prevalence of both disorders may be even higher: OSA may affect more than 50% of individuals over the age of 65, and significant depressive symptoms may be present in as many as 26% of a community-dwelling population of older adults. In clinical practice, the presence of depressive symptomatology is often considered in patients with OSA, and may be accounted for and followed-up when considering treatment approaches and response to treatment. On the other hand, sleep problems and specifically OSA are rarely assessed on a regular basis in patients with a depressive disorder. However, OSA might not only be associated with a depressive syndrome, but its presence may also be responsible for failure to respond to appropriate pharmacological treatment. Furthermore, an undiagnosed OSA might be exacerbated by adjunct treatments to antidepressant medications, such as benzodiazepines. Increased awareness of the relationship between depression and OSA might significantly improve diagnostic accuracy as well as treatment outcome for both disorders. In this review, we will summarize important findings in the current literature regarding the association between depression and OSA, and the possible mechanisms by which both disorders interact. Implications for clinical practice will be discussed.

Obstructive sleep apnea and depression

Is there an association between obstructive sleep apnea (OSA) and depression? OSA is a common breathing-related sleep disorder. There have been reports that depressive symptoms can be associated with this sleep disorder. A number of investigations have addressed this issue. Although some have found no correlation, most studies have concluded that there is an association between OSA and depressive symptoms. Other investigations have shown that depressive symptoms improve with treatment of OSA, and that untreated OSA may contribute to treatment resistance in some cases of mood disorders. Within the framework of current psychiatric diagnostic criteria, the depressive symptoms associated with OSA can be viewed as a combination of a mood disorder secondary to a primary medical condition and an adjustment disorder with depressed mood. The question of whether OSA causes depressive symptoms can perhaps be best answered by viewing OSA and depression as having certain symptoms that are common to both disorders.

To breathe, perchance to sleep: sleep-disordered breathing and chronic insomnia among trauma survivors

Standard psychiatric classification (DSM-IV-TR) traditionally attributes post-traumatic sleep disturbance to a secondary or symptomatic feature of a primary psychiatric disorder. The DSM-IV-TR paradigm, however, has not been validated with objective sleep assessment technology, incorporated nosological constructs from the field of sleep disorders medicine, or adequately addressed the potential for post-traumatic stress disorder (PTSD) sleep problems to manifest as primary, physical disorders, requiring independent medical assessments and therapies. This paradigm may limit understanding of sleep problems in PTSD by promulgating such terms as "insomnia related to another mental disorder," a.k.a. "psychiatric insomnia." Emerging evidence invites a broader comorbidity perspective, based on recent findings that post-traumatic sleep disturbance frequently manifests with the combination of insomnia and a higher-than-expected prevalence of sleep-disordered breathing (SDB). In this model of complex sleep disturbance, the underlying sleep pathophysiology interacts with PTSD and related psychiatric distress; and this relationship appears very important as demonstrated by improvement in insomnia, nightmares, and post-traumatic stress with successful SDB treatment, independent of psychiatric interventions. Continuous positive airway pressure treatment in PTSD patients with SDB reduced electroencephalographic arousals and sleep fragmentation, which are usually attributed to central nervous system or psychophysiological processes. Related findings and clinical experience suggest that other types of chronic insomnia may also be related to SDB. We hypothesize that an arousal-based mechanism, perhaps initiated by post-traumatic stress and/or chronic insomnia, may promote the development of SDB in a trauma survivor and perhaps other patients with chronic insomnia. We discuss potential neurohormonal pathways and neuroanatomatical sites that may be involved in this proposed interaction between insomnia and SDB.

Prevalence of restless legs syndrome and periodic limb movement disorder in the general population

BACKGROUND

Periodic limb movement disorder (PLMD) and restless legs syndrome (RLS) are two sleep disorders characterized by abnormal leg movements and are responsible for deterioration in sleep quality. However, the prevalence of these disorders is not well known in the general population. This study aims to document the prevalence of RLS and PLMD in the general population and to identify factors associated with these conditions.

METHODS

Cross-sectional studies were performed in the UK, Germany, Italy, Portugal and Spain. Overall, 18,980 subjects aged 15 to 100 years old representative of the general population of these five European countries underwent telephone interviews with the Sleep-EVAL system. A section of the questionnaire assessed leg symptoms during sleep. The diagnoses of PLMD and RLS were based on the minimal criteria provided by the International Classification of Sleep Disorders.

RESULTS

The prevalence of PLMD was 3.9% and RLS was 5.5%. RLS and PLMD were higher in women than in men. The prevalence of RLS significantly increased with age. In multivariate models, being a woman, the presence of musculoskeletal disease, heart disease, obstructive sleep apnea syndrome, cataplexy, doing physical activities close to bedtime and the presence of a mental disorder were significantly associated with both disorders. Factors specific to PLMD were: being a shift or night worker, snoring, daily coffee intake, use of hypnotics and stress. Factors solely associated with RLS were: advanced age, obesity, hypertension, loud snoring, drinking at least three alcoholic beverages per day, smoking more than 20 cigarettes per day and use of SSRI.

CONCLUSIONS

PLMD and RLS are prevalent in the general population. Both conditions are associated with several physical and mental disorders and may negatively impact sleep. Greater recognition of these sleep disorders is needed.

Does obstructive sleep apnea confound sleep architecture findings in subjects with depressive symptoms?

BACKGROUND

Compared with normal subjects, depressed patients have shorter rapid eye movement sleep latency (REML), increased REM and decreased slow wave sleep as a percentage of total sleep time (REM%, SWS%), and longer sleep latency (SL). Obstructive sleep apnea (OSA) patients experience longer REML, decreased REM% and SWS%, and shorter SL. We examined the interplay of depressive symptoms, OSA, and sleep architecture.

METHODS

Subjects (n = 106) were studied with polysomnography. OSA was defined as a Respiratory Disturbance Index > or = 15. Subjects were divided into Hi/Lo groups using a Center for Epidemiological Studies-Depression (CES-D) score of 16.

RESULTS

OSA patients had shorter SL than non-OSA patients (14.5 vs. 26.8 min, p <.001); Hi CES-D subjects showed a trend toward longer SL than Lo CES-D subjects (23.7 vs. 17.5 min, p =.079). Significant OSA x CES-D interactions emerged, however, for REM% (p =.040) and SL (p =.002): OSA/Hi CES-D subjects had higher REM% than OSA/Lo CES-D subjects (19.3% vs. 14.3%, p =.021); non-OSA/Hi CES-D subjects had SL (35.3 min) 2-3 times as long as other subjects (p =.002-.012).

CONCLUSIONS

Because of the high prevalence of OSA and depression, findings suggest that OSA must be considered in studies of mood and sleep architecture. Conversely, depressive symptoms must be considered in studies of OSA and sleep architecture.

Sleep Disorder, Depression, and Suicidality in Female Sexual Assault Survivors

The role of sleep in psychiatric illness in general, and depression and suicidality in particular, is poorly understood and has not been well researched despite the pervasiveness of sleep complaints in these conditions. As an exploratory, hypothesis-generating study, female sexual assault survivors with posttraumatic stress disorder (n = 153) who had enrolled in a nightmare-treatment program were assessed for subjectively determined sleep breathing and sleep movement disorders. Diagnoses of potential disorders were based on clinical practice parameters and research algorithms from the field of sleep disorders medicine. Potential sleep breathing and sleep movement disorders were present in 80% of the participants (n = 123) and included three subgroups: sleep-disordered breathing only (n = 23); sleep movement disorder only (n = 45); and both sleep disorders (n = 55). Based on the HamiltonDepression Rating Scale and Suicide subscale, participants with potential sleep disorders suffered greater depression (Cohen's d = .73-.96; p < .01) and greater suicidality (Cohen's d = .57-.78; p < .05) in comparison to participants without potential sleep disorders. The group with both sleep disorders suffered from the most severe depression and suicidality. A provisional hypothesis is formulated that describes how sleep disorders may exacerbate depression and suicidality through the effects of chronic sleep fragmentation.

Sleep breathing and sleep movement disorders masquerading as insomnia in sexual-assault survivors

A descriptive, hypothesis-generating study was performed with 156 female sexual-assault survivors who suffered from insomnia, nightmares, and posttraumatic stress disorder (PTSD). They completed 2 self-report sleep questionnaires to assess the potential presence of intrinsic sleep disorders. Seventy-seven percent of the sample (120 of 156) endorsed additional sleep complaints, besides their insomnia symptoms, that indicate the potential presence of sleep-disordered breathing ([SDB] 81 of 156, 52%) and sleep-related movement disorders ([SMD] 94 of 156, 60%). The potential for SDB was strongly correlated with the body mass index (BMI), an increase in arousal symptoms, and greater total PTSD severity. In some sexual-assault survivors, the relationship between sleeplessness and posttraumatic stress may be caused or exacerbated by intrinsic sleep disorders, and not be solely a function of psychophysiological insomnia--the traditional diagnostic term usually offered to explain the sleep problems associated with PTSD. Prevalence studies that use objective diagnostic evaluations such as polysomnography (PSG) are needed to test these hypotheses.

Obstructive sleep apnoea and depression--diagnostic and treatment implications

Sleep apnoea (OSA), a common sleep disorder, is well recognised as a cause of morbidity including psychiatric disorders. There is increasing recognition of the link between OSA and depression. Sleep changes are intrinsic to depressive disorders, most notably disturbances of REM sleep; OSA causes predominantly REM sleep disturbances. The neuro-vegetative features of depression are similar or identical to the symptoms of OSA-an issue which has not achieved wide clinical recognition. A growing number of studies confirm the statistical link between the two conditions. The implications are twofold: OSA needs to be excluded in cases of chronic or resistant depression and treatment of OSA will make it easier to treat the primary depressive disorder. A new method of treatment for OSA, the Sullivan continuous positive airway pump (CPAP), raises the theoretical possibility of treating depression by this means as well.

Sleep disorders in psychiatric practice

Sleep disorders medicine and psychiatry interface in numerous ways. Most psychiatric patients have a complaint about sleep, and regardless of the theoretical orientation of a psychiatrist, understanding of a patient's sleep function is an important part of assessment. The success or failure of treatment will be strongly influenced by the effect of that treatment on the patient's sleep disorder. The psychiatrist can provide expertise in treating patients with primary sleep disorders, offering pharmacologic consultations, and recommending psychotherapy or behavioral management. Conversely, a knowledge of primary sleep disorders should make the psychiatrist a more effective practitioner.

Self-reported excessive daytime somnolence and impaired respiration in sleep

The purpose of this study was to determine which measures of impaired respiration in sleep relate to self-reported excessive daytime somnolence (EDS). Previous studies conflict regarding the relative importance of arterial hypoxemia and brief awakenings in relating to EDS. A group of 37 elderly clinic patients with complaints of snoring, a clinical diagnosis of sleep apnea, and varying degrees of self-reported somnolence were evaluated polysomnographically and psychometrically. Results showed that a subgroup of somnolent patients were characterized by more severe oxygen desaturations relative to nonsomnolent patients. These differences were obtained even when obesity was controlled. Psychologic symptoms related to the symptom of EDS but not to the sleep measures. This suggested that patients were clearly distressed by their hypersomnolence, but that individual differences played a major role in how the distress was manifested.

A case report of obstructive sleep apnea in a patient with bipolar affective disorder

A patient with a bipolar mood disorder developed obstructive sleep apnea which altered the clinical presentation of the mood disorder and affected compliance with prophylactic treatment. Significant improvements in the management of her mood disorder and in her life adjustment followed surgical relief of the upper airway obstruction.

EEG sleep, depression, and aging

To date little attention has been paid to the possible age-dependent relationships of EEG sleep measures in depression or to the implications of such relationships for diagnostic sensitivity and specificity. In a study of 108 patients with major depressive disorders (67 inpatients, 41 outpatients), age was shown to be a very powerful determinant of electroencephalographic (EEG) sleep patterns. Thus, among other sleep variables, sleep efficiency, delta sleep percent, and REM latency all showed significant linear declines with increasing age. Similar trends were seen in both inpatients and outpatients. Some variables were without age trends (age-stable), including sleep latency, REM sleep percent, and REM activity. These findings confirm those of an earlier report from our laboratory [45] and suggest that age-corrected sleep variables can be developed for clinical diagnostic application. Thus, using normative data from Gillin et al. [19] for comparison, a sensitivity level of 65% for age-corrected REM latency was demonstrated, together with a specificity of 95% and a diagnostic confidence of 92%. Data from a pilot study comparing EEG sleep measures in depression and dementia are also presented; these data suggest the potential utility of EEG sleep measures in the differential diagnosis of these two disorders, especially in patients with mixed symptoms. Additional areas for further research are reviewed with enumeration of specific testable hypotheses.