Sutratman is the breath (prana) which performs the function of holding the body together like a thread (sutra). In the Hindu philosophical systems, sutratman is synonymous with hiranyagarbha (the cosmic golden energy or womb from which the creation of the Universe took place).
The concept of Sutratman is used in the analysis of the five sheaths of living beings. The outermost sheath is the gross body perishing with death. The pranamaya kosha (the vital sheath), the manomaya kosha (mental sheath), and the vijnanamaya kosha (knowledge sheath) form the subtle body (Sukshma Sharira which transmigrates. The innermost sheath (anandamaya kosha) is manifest only in deep sleep, while the atman transcends all these.
The term Sutratman refers to the divinity that presides over the concentration of the subtle bodies of all living beings. Each subtle body is regarded as belonging to every being. All the subconscious expressions from which conscious experience is derived are latent in this subtle body. The dream experience is a form of latent experience. So the subtle body is also referred to as swapna (dream).
Sutratman would be the macrocosmic homologue of swapna. Mandukya Karika of Gaudapada (7th century AD) analyses the three states of experience, waking, dreaming and sleeping along with their cosmic counterparts. There the shining dream body has its cosmic correlate in the hiranyagarbha or sutratman.
In Panchadasi, Vidyaranya (1350 AD) compares the world appearance with a painting where the white canvas stands for the Absolute (Brahman). The dark color stands for sutratman, the dispenser of the elements. Here Sutratman refers to the creator who presides over creation before the appearance o the manifold world.
Source – Encyclopedia of Hinduism Volume X – page 229 - IHRF