Disillusionment. The absence of illusions. That sounds like a good thing, right? We mean, if we don't have illusions, that means we're not seeing things that aren't there, which also means we're not totally insane. Awesome.
But disillusionment can have a not-so-nice meaning, too. It can mean that we've become disenchanted with life's wonder. That we can't think outside the box, believe in something more, and free up our imaginations. There's just the boring old nightgown and the boring old bed.
And that brings us to the "Ten O'Clock" portion of the title. If we're disillusioned at 10 o'clock, that means we're disillusioned right around bedtime—the time our dreams are supposed to take over. But if you're disillusioned at 10 o'clock, those dreams are gonna be, well, really boring. No flying, no baboons. Snoozerific.
It's that snoozerific quality that our speaker is lamenting. What a shame our nightgowns are so boring. What a shame we dream in black and white and not in periwinkle. In fact, you might say that even our speaker is disillusioned—with the lack of imagination these bedtime bozos are showing.