Challenging the sleep homeostat: Sleep in depression is not premature aging

Altered overnight modulation of spontaneous waking EEG reflects altered sleep homeostasis in major depressive disorder: A high-density EEG investigation

“…MDD is a heterogenous disorder (Krishnan and Nestler, 2010), and thus it is certainly plausible that uncontrolled covariates and/or unrecognized subgroups may be responsible for the findings of this investigation. One possible factor that could mediate our findings is gender, since significant sex-related effects on sleep SWA in MDD have been described, with increases in SWA among depressed women and decreases in SWA among depressed men, relative both to each other and to healthy comparison subjects (Armitage, et al, 2000a; Armitage, et al, 2000b; Armitage, 2007; Frey, et al, 2012a; Frey, et al, 2012b; Plante, et al, 2012). In addition, women with MDD have demonstrated an enhanced homeostatic response in sleep deprivation paradigms, evidenced by increased SWA during recovery sleep and waking low frequency activity, particularly in frontal EEG derivations (Armitage, 2007; Birchler-Pedross, et al, 2011; Frey, et al, 2012a; Frey, et al, 2012b).…”

Subjective Mood in Young Unmedicated Depressed Women under High and Low Sleep Pressure Conditions

“…The distribution of slow-wave activity (SWA), as indexed by the delta sleep ratio [quotient of SWA in the first to the second non-Rapid eye movement sleep (NREM) episode], was investigated in unmedicated SD responders and SD non-responders [27], whereby a high delta sleep ratio was a positive predictor for SD response. We previously described that the same MDD women as in this analysis appear to live on a higher level of homeostatic sleep pressure, as indexed by NREM EEG slow-wave activity (SWA 0.75–4.5 Hz) during baseline sleep [11,12]. Recovery sleep at the end of the high and also low sleep pressure protocols also showed significantly higher SWA in the MDD women than in controls [11,12].…”

“…We previously described that the same MDD women as in this analysis appear to live on a higher level of homeostatic sleep pressure, as indexed by NREM EEG slow-wave activity (SWA 0.75–4.5 Hz) during baseline sleep [11,12]. Recovery sleep at the end of the high and also low sleep pressure protocols also showed significantly higher SWA in the MDD women than in controls [11,12]. Moreover, MDD women responded with a stronger EEG synchronization in a frequency range of 0.5–5 Hz during SD [13], which confirmed the higher delta waves during sleep, but not the role of delta sleep as a positive predictor for the SD response.…”

“…In a similar vein, this finding was later observed in MDD individuals, albeit only in men [5]. Conversely, we previously showed that young MDD women devoid of co-morbid sleep disturbances exhibit higher, not lower, frontal non-REM delta EEG activity (0.75–4.5 Hz), a classical marker of homeostatic sleep pressure, during both baseline and recovery sleep subsequent to SD, as compared to that of healthy young and older women [11,12]. Furthermore, MDD women exhibited higher frontal low-frequency (FLA) wake EEG activity (0.5–5.0 Hz) during SD than that of healthy controls, particularly during the biological night [13].…”

“…Furthermore, MDD women exhibited higher frontal low-frequency (FLA) wake EEG activity (0.5–5.0 Hz) during SD than that of healthy controls, particularly during the biological night [13]. Together, these data indicate that young, moderately depressed women without sleep disturbances do not exhibit a deficiency in the sleep homeostatic process S, as predicted by the S-deficiency hypothesis, but may rather live on an elevated level of homeostatic sleep pressure [11,12]. Thus, concurrent sleep disturbances may play a key role both in the pathophysiology of depression and in the antidepressant response to SD.…”