Higher Frontal EEG Synchronization in Young Women with Major Depression: A Marker for Increased Homeostatic Sleep Pressure?

Abstract

Our data imply that young women with MDD live on a higher homeostatic sleep pressure level, as indexed by enhanced FLA during wakefulness. Its positive correlation with depression scores indicates a possible functional relationship. High FLA could reflect a use-dependent phenomenon in depression (enhanced cognitive rumination or tension) and/or an attenuated circadian arousal signal.

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

“…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. These results challenge a generalized assumption that “Process S” is deficient in all MDD [3].…”

“…Control and MDD women were recruited via advertisement at different Swiss universities and through online job advertisement pages for students (for details see [13]). The rationale to include only women was due to the fact that, typically, women are twice as likely to experience MDD as compared to men.…”

“…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]. 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].…”

Altered overnight modulation of spontaneous waking EEG reflects altered sleep homeostasis in major depressive disorder: A high-density EEG 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). Taken together, these data suggest that MDD women may live with or tolerate an elevated level of homeostatic sleep pressure relative to men.…”

“…Two studies that examined theta activity over the course of sleep deprivation in seasonal affective disorder (SAD) demonstrated a progressive increase in waking low frequency power in healthy subjects, which was attenuated (Cajochen, et al, 2000) or absent (Danilenko and Putilov, 2005) in SAD, suggesting altered homeostatic mechanisms in this depressive subtype. Birchler-Pedross and colleagues recently demonstrated increased LFA in MDD women relative to controls in response to extended wakefulness, with frontal LFA correlating with depression severity (Birchler-Pedross, et al, 2011). The current study sought to further examine homeostatic function in MDD using high-density EEG (hdEEG) prior to, during, and after a night of sleep.…”