narcolapsy

When you forget something due to extreme tiredness and/or not being fully awake.

A portmanteau of the words narcolepsy and lapse (as in a lapse in memory)

Ali: I didn't remember texting you last night due to a sudden case of narcolapsy LOL
Terri: You texted me last night?!?

by TeaInTheMoment May 02, 2019