Study Sample Demographics Meds at Study Measurement Target variables Results Event analysis-visual Bastien et al., 2009 [67 ] Clinical: Clinical: No Three all-night PSGs (1 adaptation); SR = ?; spindles on C3 from nights 2 & 3 Number and density of spindles (12–14 Hz activity, >0.5 sec, 20–40 μ V) during NREM2 No group differences Spectral analysis Freedman, 1986 [68 ] Clinical: Clinical: No Three all-night PSGs (1 adaptation); SR = 128 Hz; FFT on C3 and O1 from night 3 EEG power spectra from 1–30 Hz during the first unambiguous minute of each sleep stage (1) No group differences during NREM; (2) insomnia group had higher 16 Hz activity during REM on O1 Merica et al., 1998 [66 ] Clinical: Clinical: No Three all-night PSGs (1 adaptation); SR = 128 Hz; FFT w/avg of 5 Absolute sigma power (12.5–14.75 Hz) across the first four NREM-REM cycles (1) Insomnia group had slower sigma rise rate and attenuated power curve in NREM cycles 3 and 4; (2) insomnia group had higher sigma power curve across all 4 REM cycles Krystal et al., 2002 [69 ] Clinical: Clinical: No One ambulatory PSG; SR = 128 Hz; FFT w/2-sec eph on C3 Absolute and relative sigma power (12.5–16 Hz) during NREM2/NREM3 and REM (1) Higher absolute and relative sigma in SI versus OI and in OI vs. controls during NREM2/NREM3; (2) no group differences during REM Bastien et al., 2003 [70 ] Clinical 1: Clinical 1: Only benzodiazepine in the medicated group Three all-night PSGs (1 adaptation); SR = 200 Hz; FFT w/2.56-sec eph on C3 from night 2 Absolute sigma power (11.7–14.04 Hz) during the first four NREM cycles and total sleep No group differences Staner et al., 2003 [71 ] Clinical 1: Clinical 1: No Three all-night PSGs (1 adaptation); SR = 128 Hz; FFT w/2-sec eph on C3 from night 3 Spindle frequency activity (SFA: 11.5–15 Hz) for the 1st NREM cycle divided into 10 intervals, expressed as % relative to total/undivided NREM cycle No group differences Buysse et al., 2008 [72 ] Clinical: Clinical: No Three all-night PSGs (1 adaptation); SR = 256 Hz; FFT w/4-sec eph on C3 and C4 from night 2 Absolute and relative sigma power (12–16 Hz) during individual NREM cycles and total NREM (1) No overall group differences during each NREM cycle and during total NREM sleep; (2) group Forget et al., 2011 [73 ] Clinical: Clinical: No Four all-night PSGs (1 adaptation); SR = 512 Hz; FFT w/1-sec eph on Fz from nights 3 & 4 Relative sigma power (12–14 Hz) before and after spontaneous and evoked K-complexes No group differences Spiegelhalder et al., 2012 [74 ] Clinical: Clinical: No One all-night PSG; SR = 200 Hz; FFT w/30-sec eph on C3 Absolute sigma power (12–16 Hz) during NREM2 and REM (1) Total insomnia group had higher sigma during NREM2, but not during REM; (2) no group differences between SI and OI subtypes during NREM2 Israel et al., 2012 [75 ] Clinical: Clinical: No Three all-night PSGs; SR = 256 Hz; FFT w/4-sec eph on C3 and C4 Mean relative sigma power (12–16 Hz) during NREM No group differences (adjusting for age, sex) St-Jean et al., 2013 [48 ] Clinical 1: Clinical 1: No Four all-night PSGs; SR = 512 Hz; FFT w/4-sec eph on F3, F4, Fz, C3, C4, Cz, P3, P4, Pz from nights 2 & 3 Absolute and relative sigma power (11–14 Hz) during selected portions of stable, consolidated, and artefact-free periods of NREM1–4 (“NREM”) and REM (1) SI had higher absolute sigma versus OI on F3 and F4 during NREM; (2) SI had lower relative sigma versus OI on F3 and F4 during REM; (3) SI had lower relative sigma versus controls on all frontal and central derivations during REM; (4) SI had lower relative sigma versus OI and versus controls on F3, F4, and Fz during NREM-REM cycle 4 Wu et al., 2013 [76 ] Clinical: Clinical: No Three all-night PSGs (1 adaptation); SR = 256 Hz; FFT w/4-sec eph on C3 and C4 from night 2 Absolute and relative sigma power (12–16 Hz) during the first NREM period and total NREM No group differences Cervena et al., 2014 [77 ] Clinical 1: Clinical 1: No Three all-night PSGs (1 night for controls); SR = 256 Hz; FFT w/15 Absolute sigma power (12–14.75 Hz) during the 5 mins before and after sleep-onset divided into 1-min intervals No group differences Maes et al., 2014 [78 ] Clinical: Clinical: No Retrospective analysis of one all-night PSG; SR = 250 Hz; FFT w/4-sec eph on C4 Relative sigma power (12–16 Hz) during sleep-onset, first SWS cycle, and within 1 sec of a NREM2 K-complex No group differences
