sleep and dreams
How does Patanjali's Yoga Sutra treat sleep (nidra) as a mental modification (vritti)?
What the Yoga Sutras say
Patanjali lists five types of vritti, the movements or modifications of the mind. They are right knowledge, wrong knowledge, imagination, sleep, and memory. Sleep, called nidra, is the fifth. This surprises many people. Sleep feels like the mind switching off, so why count it as a mental movement at all? Patanjali's answer is that nidra is its own kind of vritti, one that rests on the experience of absence. The mind is not blank in sleep. It takes on a particular quality, the quality of heaviness and void. That quality is itself a modification. When you wake up and say you slept well or slept badly, that report comes from somewhere. The mind was doing something, even if that something was registering emptiness.
How commentators explained it
An early commentary on the Yoga Sutras, the Vyasa Bhashya, worked through this idea carefully. It pointed out that if sleep were truly nothing, there would be no memory of it on waking. But people do remember sleep, or at least its quality. That memory proves the mind was active in some form. So sleep is not the absence of mind but a specific state the mind enters. This reading helped later teachers explain why even deep, dreamless sleep does not count as the stillness yoga is aiming for.
What this means for practice
The goal of yoga, in Patanjali's framework, is to still all the vrittis, including nidra. This matters because it draws a clear line between sleep and the deep stillness of meditation or samadhi. Sleep might feel peaceful, but the tradition holds that it is not the same as genuine inner quiet. In sleep, the mind is still caught in a modification, just a dull one. True stillness, by contrast, is alert and clear. So the practitioner is not trying to fall asleep in meditation. They are trying to reach a state that goes beyond all five vrittis, sleep included.
How people engage with this today
This teaching comes up often in yoga philosophy classes and retreats. Many students find it counterintuitive at first. The idea that sleep is something the mind does, not just something that happens to it, shifts how people think about rest and awareness. Some teachers use it to explain why meditation and sleep feel different even when both involve closed eyes and stillness. The concept of nidra also appears in the name of yoga nidra, a guided relaxation practice, though that practice draws on the idea in its own way and is a separate development from Patanjali's original text.