Laying down after yoga is an important step that should not be skipped. Laying down allows your energies to amplify. You do not need to lay down for 15 minutes. You only need to lay down until you get an "energy buzz," which is a feeling of lightness, tingling, buzzing, glowing, etc. The "energy buzz" indicated your energies have been successfully amplified. You can lay own for as little as 3-5 minutes if that is all you need.