Green’s Dictionary of Slang

sniffles, the n.

[SE sniffles, weeping, tearfulness]

(US) a fit of depression.

[US]A. Adams Log of a Cowboy 279: ‘I hope you won’t get the sniffles and tell any.’ ‘This letting yourself get gloomy [...] reminds me of the time we once had at the ‘J.H.’ camp.’.