I find that how much sleep I need depends on how present and moral I feel in my life in general at that time.<p>At one extreme, I once attended a week and a half meditation retreat in which you're up at 4, meditating for about 11 hours every day and the whole thing is silent. I felt such heightened moral and mental clarity by the fifth and sixth days that I began sleeping less, sometimes lying awake until 2 or 3am (and up at 4), but felt full of energy each day.<p>At the other extreme, carrying on in a big city, I indulge in vices, deviate from my notion of perfect morality, exaggerate in conversations, eat meat, engage in reactive behavior with others, fail to keep up a meditation routine etc., and I end up sleeping 7-8 hours like clockwork.<p>I have a twofold theory
1. Internal monologue creates excess pathways in the brain that need to be pruned, creating the need to sleep. Decreasing the amount and degree of our internal monologue (sometimes called 'being present') decreases the amount of these pathways and thus the sleep we need.
2. Failure to act rightly/morally/virtuously creates the need to sleep. The more our daily actions are in line with our sense of right action, right morality, the less sleep we will need. The deeper theory here is that immoral acts cause neurological agitation that creates toxins in the brain that sleep flushes away.<p>My theory is supported by my understanding of sleep as having the function of 'flushing toxins' from the brain and 'pruning' neurological pathways that the brain determines not useful, such as a thought you had that day in your internal monologue. Immoral acts tend to nag at us, even if only a little act and a little bit, creating anxious internal monologue, compounding the need for sleep.