There are two reasons for the inability to sleep – one reason is worry and the second reason is desire. If you have a desire or a worry you will be unable to sleep. If you do yoga nidra before sleeping you can free yourself from worry and the mind will attain the state of sleep.
What is the effect of yoga nidra on the human brain? In the human brain four kinds of electrical waves are produced, beta, alpha, delta and theta waves. Beta waves are produced when there is restlessness in the brain. At that time the tendency of the person is extroverted. Currently the beta waves are prominent in your brain, for you are extroverted and in that state the senses and the mind remain restless.
When you go to bed in the evening or afternoon, and you close your eyes and make an effort to relax yourself for five minutes, the beta waves are reduced and the alpha waves increase. The state of physical relaxation is indicated by alpha waves in the brain.
The state of physical agitation is indicated by the emergence of beta waves in the brain. At the time of worry and anxiety when you are passing sleepless and restless nights, worry and anxiety are keeping your beta waves active in the brain, and you are unable to sleep. If you practise yoga nidra you are able to convert the beta waves into alpha waves.
You will see that before you complete the practice of yoga nidra you start another practice which is known as snore nidra. Therefore, start with yoga nidra at night and move into snore nidra.
—21 September 2014, Tyagaraj Sports Stadium, Delhi, India