Does Buddha ever talk about his daily routine? I heard that he sleeps only 4 hours.
There is also the wonderful new book by Bhante S Dhammika,
“Footprints in the dust; the life of the Buddha from the most ancient sources.”
The four hours of sleep thing comes from the way people marked time those days. They, of course, didn’t use hours like we do.
One feature of the Buddha’s day that is ubiquitous in the commentarial stories but is (completely?) absent from the suttas is the time he took each day to survey the world with his mind to see if there was anyone who could use his help to either attain stages of enlightenment or at least be reborn in heaven.
I think the closest we get in the suttas is when he saw that his son, Venl Rāhula, had the necessary conditions to attain full enlightenment.
Ven. Bhikkhu Bodhi mentions Devata Samyutta. He believes that the Buddha had conversations with devas at night!
Regarding Deveta Samyutta, Choong Mun-keat has published the following article:
"A comparison of the Pali and Chinese versions of the Devata Samyutta and Devaputta Samyutta , collections of early Buddhist discourses on devatas “gods” and devaputras “sons of gods” ", Journal of the Oxford Centre for Buddhist Studies, vol.1, October 2011, pp. 60-88.