During sleep we experience two patterns of sleep namely non- REM sleep (randomised eye movement) and REM sleep, which follow one another in episodes.
The rapid eye movement of REM sleep can be recorded by electrooculogram (EOG), atonia is recorded by the electromyograom (EMG), and the waking activity is recorded by the electroencephalogram (EEG).
Thus, the blank can be filled with electrooculogram (EOG); electromyograom (EMG); electroencephalogram (EEG).