Green’s Dictionary of Slang

1. intoxicated by drugs.

1968		N. von Hoffman We are the People Our Parents Warned Us Against 42: Dope slogans like ‘turned on,’ ‘switched on’.
1976		in Kay 6000 Words.

2. sexually stimulated.

1965		P. Wylie Esquire July 44–45: switched-on — [...] agitated as ‘that switches me on’.
1968		Current Sl. II:4 10: Switched on, adj. Excited, enthusiastic [...] — She was switched on about him.
1977		D. Powis Signs of Crime 204: Switched on Aroused by music or by sexual overtures. Can be used in female company.

3. aware, sophisticated, up to the minute.

1965		P. Wylie Esquire July 44–45: switched-on—enthusiastic, interested.
1969		N. Cohn Awopbop. (1970) 191: The authoritative voice of trendy, deeply switched-on and sinful female youth.
1999		Guardian Guide 14–20 Aug. 12: I love the idea of these old guys doing switched-on, tripped-out tribal music for the kids.
2000		Guardian Editor 17 Mar. 9: They are cracking kids ... Really switched on.
2010		L. Redhead Thrill City [ebook] She seemed like a pretty switched-on old cookie.
2011		Guardian Mag. 30 Apr. 33/5: I’m sure today’s models are a lot more switched-on than we were.
2023		R. Milward Man-Eating Typewriter 188: Switched-on mod-pops with arriss length skimpies and peacock clobber.