Have you experimented with sleep posture? A cursory search turned up a 2000 study showing that sleeping in a supine position might contribute to lucid dreams. Some of the subjects suffered from hypnopompic sleep paralysis:
Dahmen N; Kasten M. REM-associated hallucinations and sleep paralysis are dependent on body posture. Journal Of Neurology, 2001 May; Vol. 248 (5), pp. 423-4
Many of these factors seem, with high probability, like genuine constraints (e.g. a second generation star). But I wonder whether others might be examples of anthropic generalizing from one example (e.g. availability of a specific ratio of elements). Presumably alien life would adapt to whatever conditions actually exist in their world.