Yoga nidra is a systematic method that induces complete mental, emotional and physical relaxation that is suitable for everyone.
One typically lies down in savasana (or sits) and is supported by pillows and guided into a meditation in which you learn to relax consciously. You remain awake and aware throughout nidra.
Swami Satananda Saraswati
"Yoga nidra is a more efficient and effective form of psychic and physiological rest and rejuvenation than conventional sleep. Those that adopt this technique in their daily routine soon experience profound changes in their sleeping habits. The total systematic relaxation of a yoga nidra session is equivalent to hours of conventional sleep."