The relaxation time to a Maxwellian energy distribution is determined experimentally for the electrons in a pulsed discharge. The electron energy distribution relaxes to a Maxwellian distribution a few microseconds after the beginning of the pulse. This result can be used to discuss several hypotheses which have been advanced to explain the Langmuir paradox. In the opinion of the authors, the most likely explanation is a mechanism in which an equilibrium distribution is produced by the high-frequency oscillations of the double sheath near the wall; this is the only mechanism capable of producing a Maxwellian energy distribution for the electrons in the brief time which is observed experimentally.