Recently, approximately one hundred genes whose brain expression is increased during periods of sleep have been found.[38] A similar number of genes were found to promote gene expression during wakefulness. These sets of genes are related to different functional groups which may promote different cellular processes. The genes expressed during wakefulness may perform numerous duties including energy allocation, synaptic excitatory neurotransmission, high transcriptional activity and synaptic potentiation in learning of new information.