"1. The optimal wake feature reduces daytime grogginess only in the sense that it puts you in a better mood in the morning. 2. Yes it is very unlikely to have adverse effects. You are just waking a little bit earlier at a point where your body feels more inclined to wake up."

Two claims. No data from either published literature (from other studies) or their own data. How do they even know it works? Why should we treat it any differently than claims of magnets improving your sleep? A free pass shouldn't be granted just because they are YC.