You are so tired that drawing attention away from the immediate situation is too much effort and quickly peters out. But what is the immediate situation? Beneath the grey pall of tiredness the mind remains fresh and active, it is just that these qualities are no longer at your disposal. Every thread of interest which normally serves to define you, those in which you fully participate because their reflections and echoes bring forth a privately social pleasure, every one of these now seems no more than an effort, the assuming of a mask, and it has fallen away. You are too tired to have an identity, and this is its own kind of pleasure but is also a great bore, just keeping minimally awake for nothing. In normal waking life an identity and its prerogatives seem to be a mere entitlement and your natural state, the bizarre and self-contradictory volatility of identity is irrelevant. When energy is abundant and is then used to give fire to identities with few cares, then the expenditure, the economics of the process, is unnoticed and even seems not to exist. You merely seem to be expressing your essence out of its self-sufficient over-flow.