Despite attempts to globally classify microsleeps through these detection methods (with particular emphasis on EEG and slow eyelid closure tests), there is great variability in the types of microsleeps that people experience.[32] Subjective, self-reported psychological tests like the Karolinska Sleepiness Scale (KSS), though widely adopted and positively correlated to EEG, often have limited utility because individuals sometimes are not aware of their level of sleepiness.[33] Future research needs to focus more on objective microstates (e.g. detailed electrical output in briefer intervals) that underlie microsleep events so that electrical events can be understood in terms of behavioral events with greater accuracy.[34] Then microsleep events could be more seamlessly distinguished from other states of consciousness, such as silent consciousness experienced during meditation.[35]