Is CYP1A2 useful for sleep?

CYP1A2 is not a sleep gene per se. It encodes the main enzyme that metabolizes caffeine. Variants (fast vs. slow) determine how long caffeine stays active. Slow metabolizers (CYP1A2*1F) may experience prolonged alertness and poorer sleep if they consume caffeine in the afternoon or evening. The evidence is mechanistic (enzyme kinetics) and observational; no RCTs show that genotype-guided caffeine avoidance objectively improves sleep. Thus, its usefulness for sleep is indirect and individual. For sleep problems, standard sleep hygiene (light, screens, stress) should be addressed first. A DNA test can provide a hint, but it does not replace medical evaluation for insomnia. Many other factors (e.g., ADORA2A, melatonin) have stronger effects. Evidence grade: mechanistic.