Erratum to: Amino Acids (2009) DOI 10.1007/s00726-008-0203-x

In the published original version of this article, first page, Abstract, 15th line, the information regarding the potency of NMDA (“less”) is not given correct.

The correct sentence should read:

Although NMDA also induced a sedative effect, the potency of NMDA for sleep-like behavior was less than that of glutamate.