Rihanna Parties in NYC Until Morning After Met Gala

When the sun shines, we all shine together -- especially when Rihanna's one of the first people there to greet you at daybreak after a night of celebrating an epic Met Gala.

We got RiRi leaving a couple NYC nightclubs early Tuesday morning -- the first one being Up&Down, where she hosted her own after-party, and the second (and presumably last) being 1 OAK ... walking out at the buttcrack of dawn. Must've been a helluva night.

Her outfit spoke volumes, too, about her plans afterward. Considering she looked like she was rocking some snazzy PJs ... we're guessing she was thinking ahead for bedtime.