The Black Sleep of the Kali Ma was a trance a person fell under if they drank the Blood of Kali. After drinking the blood, the victim would be put in a room surrounded by burning candles until the Black Sleep took over their mind. It was described as if being in a nightmare, unable to wake. Those under the influence of the Black Sleep were mindlessly, unswervingly loyal to Kali and the Thuggee cause, as well as being highly obedient to Mola Ram.
The only means of bringing a person out of the Black Sleep was to induce enough pain that would snap them out of it, particularly by burning the victim. If they were snapped out of the trance, the victim was completely aware of their actions and experiences while under the effects of the Blood of Kali.
Behind the scenesEdit
In early drafts of Indiana Jones and the Temple of Doom, the burning Sankara Stones actually release Mola Ram from the Black Sleep of the Kali Ma before he falls to his death, hinting that he may not have been in control of his actions.