To be so tired that it would seem to others that you are, in a sense, high. Most commonly happens late at night, and symptoms include random bursts of laughter and well, other stuff people do when there high.
Jacob-hehehehe look at that door, its so, white and beautiful.
John-ya jacob, u a little night high or what?
The physical and/or mental state in the very late hours where you are tired and not in control or just not caring about what you say or do. Easily avoided by going to sleep or drinking excess amounts of high caffine products.
Last night John was speaking nonsense about some magic unicorn steal his lucky charms??!
Oh he musta had a night high...he shouldnt stay up so late.