In modern times, Satyananda Saraswati claimed to have experienced yoga nidra when he was living with his guru Sivananda Saraswati in Rishikesh. He began studying the tantric scriptures and, after practice, constructed a system of relaxation which he popularized in the mid-20th century. He explained yoga nidra as a state of mind between wakefulness and sleep that opened deep phases of the mind, suggesting a connection with the ancient tantric practice called nyasa, whereby Sanskrit mantras are mentally placed within specific body parts, while meditating on each part (of the bodymind).