Study of dark state formation in different quantum systems, such as optically excitedatoms and molecules [1], artificial atoms in superconducting circuits and excitons, is one of developing field of modern quantum optics. Dark (decoupled) states are decoupled from other states in multilevel quantum system thus preserving its population for the time of the dark state’s existence. This feture is a key point for almost a complete population transfer between energy levels during Stimulated Raman Adiabatic Passage (STIRAP), Electromagnetically Induced Transparency, and so on. We present here a treaty on formation of dark states in HF components of sodium atom.