Buerger waves (alpha waves) of EEG have the rhythm per sec of

Stages of sleep and rhythm -        Beta rhythm- Alert, awake, maximum concentration- 13-30Hz -        Alpha rhythm- Eyes closed, mind wandering, less attentiveness- 8-13Hz -        Theta rhythm- Stage 1 NREM- 4-7 Hz -        Sleep spindles, K complex- Stage 2 NREM -        Delta rhythm- Deep sleep (Stage 3 & 4 NREM)- 3-5 Hz -        Beta Rhythm and occasional alpha rhythm- REM