From Phys.Org:
Practicing yoga nidra—a kind of mindfulness training—might improve sleep, cognition, learning, and memory, even in novices, according to a pilot study published in the open-access journal PLOS ONE on December 13 by Karuna Datta of the Armed Forces Medical College in India, and colleagues. After a two-week intervention with a cohort of novice practitioners, the researchers found that the percentage of delta-waves in deep sleep increased and that all tested cognitive abilities improved.
Unlike more active forms of yoga, which focus on physical postures, breathing, and muscle control, yoga nidra guides people into a state of conscious relaxation while they are lying down. While it has been reported to improve sleep and cognitive ability, those reports were based more on subjective measures than on objective data. The new study used objective polysomnographic measures of sleep and a battery of cognitive tests. Measurements were taken before and after two weeks of yoga nidra practice, which was carried out during the daytime using a 20-minute audio recording.
More here.