The latter, also known as “increased REM sleep pressure,” is described as a greater amount of REM sleep, mostly in the beginning of the night (also reflected by a shortened REM onset latency) and as an increase in the actual number of REMs during this sleep stage (REM density).99,100 Many studies have suggested that the REM sleep disinhibition profile is not pathognomonic for major depression, but provides evidence of antidepressant-responsive conditions. Inhibitors,research,lifescience,medical Thus, beyond depression, shortened REM sleep latencies have been more reliably reported in conditions for which antidepressant drugs are recognized as effective, such as obsessive-compulsive disorder,101 panic disorder,102 generalized

anxiety disorder,103 or borderline personality disorder.104 Polysomnographic recordings in some patients with anorexia nervosa105 and alcohol dependence106 could also demonstrate a shortened REM latency, but a depressive Veliparib side effects comorbidity was clearly present. In 1982, McCarley posited that an imbalance between

aminergic and cholinergic influences Inhibitors,research,lifescience,medical underlie REM sleep disinhibition in depressive disorder.107 Conventional supports for the imbalance theory are based on the fact that the REM sleep suppressant effect of antidepressant drugs might be attributed to facilitation of noradrenergic and/or serotonergic Inhibitors,research,lifescience,medical function or cholinergic blockade. In some cases, as with most tricyclic antidepressants, all three mechanisms may be involved. Antidepressant drugs devoid of clear-cut REM-suppressant effects (ie, bupropion,

mirtazapine, nefazodone, tianeptine, trazodone, Inhibitors,research,lifescience,medical and trimipramine) share one characteristic: their potency to inhibit noradrenergic or serotonergic uptake is absent, doubtful, or moderate.108 There are several other arguments in favor of the aminergic/cholinergic imbalance theory. A recent [18F]selleck chem Belinostat deoxyglucose positron emission tomography (FDGPET) study by Nofzinger et al109 of waking to REM sleep changes reported that, compared with healthy subjects, depressed patients showed increased activation of the brain stem reticular formation limbic and anterior Inhibitors,research,lifescience,medical paralimbic cortex, and the executive cortex during REM sleep. The authors suggested that GSK-3 their findings could reflect the disinhibition of the REM-on cholinergic neurons either directly (brain stem activation) or indirectly (through cortical projections). Other evidence comes from studies administering different cholinergic-enhancing drugs (physostigmine, arecoline, RS86) in depressed patients. These compounds induced, to various degrees, stronger signs of REM sleep disinhibition than in healthy controls, as well as, for some of them, an increased rate of awakenings and arousals.110 Other convincing arguments come from the monoamine depletion paradigms. αa-Methyl-para-tyrosine, which inhibits catecholamine synthesis, provoked REM sleep abnormalities in humans.