Two all-night PSGs (1 adaptation); SR = 128 or 256 Hz; FFT w/2-sec eph on C3 or C4 from night 2
Absolute and relative EEG power in 1 Hz bins from 0.5–25 Hz during NREM1–3 and REM, and for CAP measures during NREM2 and SWS
NC had higher absolute power across bins ranging within 5.5–18.5 Hz only within CAP A3 subtype during SWS, possibly reflecting arousal activity coinciding with sleep instability
Two all-night PSGs (1 adaptation); SR = 512 Hz; FFT w/avg of 5 4-sec eph on C3 from night 2
Absolute sigma power (12–15 Hz) during all-night NREM and REM; time course of relative spindle frequency activity (SFA; 12–14 Hz) across and within NREM cycles
(1) No group differences in absolute power; (2) no group differences in evolution of relative SFA across NREM cycles; (3) U-shaped pattern of SFA in NC only evident within the first NREM cycle, but seen within all NREM cycles among controls
Bilateral spindle density (12–14 Hz, >0.5 sec, >20 μV) calculated in 10-min segments of NREM2 and averaged; time-course of spindle density across each hour of sleep
(1) Total clinical group had greater overall mean spindle density versus controls, especially at the beginning and end of sleep time; (2) spindle density greater in IH versus narcolepsy only in the middle hours of sleep time; (3) spindle density in IH did not decline across the night as in other groups
Two all-night PSGs (1 adaptation); SR = 128 Hz; FFT w/2-sec eph on C3 or C4 from night 2
Absolute and relative sigma power (11.5–15.5 Hz) during NREM2, SWS, and REM divided into 4 90-min periods
(1) Overall group effect (NC > IH > controls) for absolute sigma during REM in the 3rd 90-min period; (2) overall group effect (NC > IH > controls) for relative sigma during whole-night SWS, and during SWS and REM in the 2nd 90 min period
Two all-night PSGs (1 adaptation); SR = 100 Hz (minimum); spindles (using FFT w/1-sec eph) from left (Fp1, C3, O1) & right leads (Fp2, C4, O2) from night 2
Mdn number and density of bilateral spindles on frontal, central, and occipital derivations; Mdn spindle frequency across 5 NREM cycles, each divided into 10 equal segments
(1) No group differences in number and density of spindles; (2) OSA had almost consistently slower spindle frequencies, with 30–70% of 10 equal segments among each NREM cycle showing significant differences
Two all-night PSGs; SR = 200 Hz; auto spindle detection from power spectra on C3 and C4 from night 2
Number of detected spindles (9.8–16 Hz), and the evolution of spindle frequencies across and within individual sleep depth cycles
(1) No group differences in the number of detected spindles; (2) mean spindle frequency lower in OSA (11.7 Hz) than controls (12.5 Hz) across the night and within sleep depth cycles 3–5
Three all-night PSGs (1 adaptation); SR = 128 Hz; integrated digital filter analysis on C3 and C4 from night 2
Sleep spindle index (SSI; 13–17 Hz) during total sleep, and in each of NREM2, NREM3, and REM sleep, both overall and across consecutive sleep cycles
SSI lower in SDB versus controls (a) during total sleep, (b) within each of four consecutive NREM-REM sleep cycles, and (c) during each of NREM2 and NREM3 examined both overall and across consecutive sleep cycles
One all-night PSG; SR = 256 Hz; Auto spindle analysis on frontal (F3 + F4), central (C3 + C4), and parietal (P3 + P4) leads
Frequency variations (“chirp”) of spindles (11–16 Hz, divided into (<13 Hz) and fast (≥13 Hz) types) measured from 3 10-min segments of NREM2
(1) Moderate OSA had a decreased percentage of decelerating spindles among frontal and parietal slow spindles versus mild OSA and versus controls, but not between mild OSA and controls; (2) moderate OSA had a loss of spindle deceleration (i.e., decline in Hz/time) versus mild OSA and versus controls among parietal slow spindles
One all-night PSG; SR = 128 Hz; FFT w/avg of 6 4-sec eph on C3
Absolute sigma power (12.25–15 Hz; overall and in 1 Hz bins) in 5-min segments averaged across total NREM-REM sleep, and both NREM and REM separately
(1) Total clinical group had higher sigma (12.25–15 Hz) power versus controls during total sleep, but no differences among clinical subgroups reported; (2) all clinical groups had lower 13-14 Hz activity versus controls during NREM, but no differences between clinical subgroups reported; (3) no group differences during REM
One all-night PSG; SR = 100 Hz; FFT w/6 4-sec eph on C4
Relative sigma power (12–16 Hz) during NREM, REM, and Total sleep (both with and without surrounding respiratory events)
(1) No between-group differences; (2) higher sigma power during NREM and total sleep within OSA group after, versus before, individual respiratory events, particularly those with associated arousals
