Three sessions, read · 2 of 3
Session 02: ten minutes of eyes closed, and a state I kept sliding out of
The longest of the three recordings, and the cleanest posterior contact of any of them. Alpha rose as expected and theta rose with it, which is the settled-rest signature rather than the slide toward sleep I first read into it.
Seagreen donkey · 10:10 · 156,064 samples · 254.52 Hz
The reading
This is settled rest, not sleep. Posterior alpha climbs from 4.9% averaged over the first three minutes to 12.4% over the last three, the expected eyes-closed alpha surge, and confirmation the tag on this recording is honest.
Theta climbs with it. At CP4, where theta is largest, it goes from 16.8% to 20.0% and reaches 24.7% in the final minute; on the same posterior sites carrying the alpha rise it is smaller but moves the same way, 6.8% to 9.6%. Alpha and theta rising together is the settled, nondirective-rest signature. Sleep onset runs the other way, alpha falling away while theta keeps climbing, and that is not what these ten minutes show.
The posterior channels here are the cleanest of any session read: CP3 at RMS 29, PO3 at 45, PO4 at 52. F5 runs eight times the channel median and should be excluded, but it sits far from the electrodes carrying this finding.
Electrode quality
Alpha and theta across ten minutes
Posterior alpha rises as I settle; central-parietal theta rises alongside it.
Band power by electrode
What each band means is on Console Decoded, which explains the five bands and the eight electrode positions in one place rather than repeating them per session.
Table view, every figure above
| Electrode | RMS | Delta | Theta | Alpha | Beta | Gamma |
|---|---|---|---|---|---|---|
| CP3 | 29.1 | 76.8 | 10.8 | 6.0 | 5.0 | 1.4 |
| C3 | 214 | 79.8 | 18.7 | 0.9 | 0.5 | 0.2 |
| F5 | 1,368 | 83.7 | 10.7 | 3.7 | 1.8 | 0.1 |
| PO3 | 44.8 | 77.3 | 8.8 | 7.4 | 5.1 | 1.5 |
| PO4 | 52.2 | 77.7 | 8.6 | 7.1 | 5.0 | 1.5 |
| F6 | 171 | 79.0 | 17.9 | 1.4 | 1.3 | 0.4 |
| C4 | 203 | 80.3 | 17.5 | 1.1 | 0.9 | 0.2 |
| CP4 | 177 | 75.3 | 20.6 | 2.0 | 1.5 | 0.5 |
What I set out to record
A long eyes-closed rest, with nothing to do and nothing to attend to. This is the control condition for everything else on the site: it is the state that should produce the largest, most reliable posterior alpha an eight-channel headset can show, so if it does not appear here it is not going to appear anywhere.
Ten minutes is also long enough to answer a question five minutes cannot. A short rest tells you whether alpha rises. A long one tells you what happens after it does.
What the traces showed
Alpha rose, and it kept rising past the point I would have called settled. It is not a smooth climb: there is a real dip in minute six on both posterior channels, then a second peak at minute eight higher than the first. Read minute by minute, this is not one state held for ten minutes, it is a state I kept sliding out of and back into.
The theta line is the one I first read the wrong way round. Plotted here at CP4, where it is largest, it sits above alpha for the whole recording and finishes at its highest value of the session. Posterior theta, measured at the same sites as the alpha rise, is much smaller but climbs in the same direction. Alpha and theta rising together over a long rest is the settled-rest pattern rather than the beginning of sleep. To call this sleep onset I would need to see alpha fall away while theta kept climbing, and across these ten minutes it does not.
The contact here is the best in the set. CP3 at RMS 29 is the quietest channel across all three recordings, and both posterior sites are under 55. F5 is the exception at eight times the median and should be dropped, but it sits at the front of the head and carries none of this argument.
What I concluded
The tag on the file is honest, which is worth saying because it is the only one of the three where I could check the label against the physiology and have it agree.
A long eyes-closed rest can slide toward sleep, and I would not claim these ten minutes could not have. What I can say is that the traces do not show it: the direction that would evidence it, alpha giving way while theta rises, never appears.
The more useful conclusion is about session length. I recorded ten minutes because longer felt more rigorous. What ten minutes actually bought me was five minutes of the state I wanted and five minutes of drifting out of it, and no way to tell those apart without reading the minutes separately. If the goal is a clean rest baseline, shorter and repeated would give me more usable signal than one long sitting.
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This site covers what the documentation doesn't: the things I wish someone had handed me first.