Dietary intervention with branched-chain amino acids—precursors for de novo glutamate synthesis—improves sleep disturbances after brain injury in mice, in part through activation of orexin neurons. Mild brain injury in mice caused a persistent inability to maintain wakefulness and decreased orexin neuron activation during wakefulness. Feeding mice a dietary supplement of branched-chain amino acids reinstated activation of orexin neurons and improved wake deficits in these animals.