Ventrolateral preoptic nucleus

The ventrolateral preoptic nucleus (VLPO) is a group of neurons in the hypothalamus. They are primarily active during sleep, and inhibit other neurons that are involved in wakefulness. The VLPO neurons release the inhibitory neurotransmitters galanin and GABA to inhibit the monaminergic cell groups in the locus coeruleus, the raphe, and the tuberomammillary nucleus (Saper, Scammell, & Lu 2005 ).