Background: One night of total sleep deprivation or of late-night partial sleep deprivation (PSD) produces a temporary remission in approximately 40-60% of patients with major depressive disorder; however, little is known about polysomnography (PSG) characteristics of responders to these types of sleep deprivation (SD).
Methods: Twenty-three unmedicated unipolar patients (17-item Hamilton Depression Rating Scale (HDRS17) >16) and 14 normal controls underwent 1 night of late-night PSD (awake after 3 a.m.) Subjects underwent baseline PSG and received the HDRS17 at standard times before and after PSD. Clinical response was defined as a reduction of >30% in the modified HDRS17 (omitting sleep and weight loss items) following PSD.
Results: The 12 responders and 11 nonresponders did not differ from each other significantly on baseline HDRS17 or PSG variables. The only PSG variable correlating with percent decrease in modified HDRS17 was baseline REM density (Pearson's r=-0.52, n=23, P=0.01.) In other words, the lower the baseline REM density, the more robust the antidepressant response was.
Limitations: Subject numbers are relatively small.
Conclusions: Increased REM density, which reflects the number of rapid eye movements per epoch of REM sleep, may be a physiological marker for severity or poor prognosis in a variety of psychiatric disorders, including relapse in recovering alcoholics, suicidality in schizophrenia, and poor response to PSD or interpersonal psychotherapy in depression.