IGF1 and sleep disorder: Compared with non-smokers, the levels of IGF1 in CSF were significantly lower among active smokers (median levels of 33.0 ng/mL vs. 35.1 ng/mL, P < 0.001), while significantly higher in PSQI scores were observed (4.02 ± 2.27 vs. 2.60 ± 2.46, P < 0.001), particularly for sleep disturbance, sleep latency, and sleep quality.