Lórien and Mandos are the Fëanturi, masters of spirits. Lórien the younger is the master of visions and dreams. His gardens in the land of the Valar at Lórien, where he dwells with Estë the gentle, healer of hurts and weariness, are the fairest place the world and are filled with many spirits. All those who dwell in Valinor find rest and refreshment at the fountain of Irmo and Estë.
When the Sun and Moon were originally set in their paths "Varda purposed that the two vessels should journey in Ilmen and ever be aloft". It was largely due to the prayers of Lórien and Estë, "who said that sleep and rest had been banished from the Earth", that Varda changed her council and allowed a time of night.
Irmo means Desirer or Master of Desire, he is also given the title Master of Dreams.