Naropa's Yoga Of Sleep utilises practices of very simple chakra visualisation (basically just points of light without much imagery) + mantra (again very simple 1-word utterances) + breath coordination (easy) that are performed sequentially during the sleep time with a waking interval of 2hrs. I was quite stoked to discover that they worked flawlessly from the first go (after simply reading a book and committing to the practice), new dimensions for mind exploration have opened up and allowed to clear lots of doubt on the shaky path of seeking truth.
"By visualising a specific chakra, the subtle winds (which follow the mind), enter the central channel. The chakra at which they enter is important in order to realise specific practices, for example, meditating on the syllable 'Ah' in the navel chakra is important for the practice of Tummo, or inner fire, the basis of the 6 yogas of Naropa. Meditating on the 'Hum' in the heart chakra is important for realising the Clear Light of bliss and emptiness. Meditating on the throat chakra is important for lucid dreaming and the practices of dream yoga. And meditating on the crown chakra is important for consciousness projection, either to another world, or into another body." (Naropa)
Generally speaking, just knowing about chakras is already doing its wonderful job, redirecting the normally wondering senses within. But practicing Yoga Of Sleep (do not confuse with Yoga Nidra, it is another meditation) opens up the portals to the subconscious mind and allows to seek guidance within through lucid dreaming and ability to decipher the mind's keys.