"Strung out on Heaven's high, hitting an all-time low" ;D

The sequel to Space Oddity, though I question whether either song need be interpreted as a drug song - I've always interpreted the "high" as a double metaphor. Why bother with the line "strung out on heaven's high" if you're talking about a drug experience? I always figured that both songs were about emotional states and perhaps the transition to mental illness. Guess the final arbiter in that discussion would be David Bowie.