It's hard to say what this tells me about my hypothesis that the 7 mg patch increases HRV. It really depends on their blood levels. The second-hand smoke machine is extremely unrealistic. They were exposed to 30 puffs of 1.8% nicotine e-juice in the first measurement interval. Assuming 150 puffs per ml, that's 3.6 mg smoked in a single 15 minute interval! I've not read the full study to confirm this calculation. Nonetheless, it's clear that these insane conditions require scrutiny. That's not even counting the fact that there's no placebo (Or even control). How am I supposed to know if this is not just an effect of being concern about inhaling e-smoke? I'm still searching for studies on low concentration of nicotine and HRV.