Your initial questions:

1. The optimal wake feature reduces daytime grogginess only in the sense that it puts you in a better mood in the morning. Attacking daytime grogginess is something we address with the analytics portion of our product.

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.

Your last question:

The optimal wake portion of our product is addressed towards people who don't particularly like waking up in the morning. If that isn't you then no, it probably isn't that useful. The other part of our product, the analytics portion, is addressed to those who want to improve their sleep quality so they can feel better rested throughout the day. It sounds like that is more what you are looking for.

tl;dr The WakeMate wakes you up at the optimal time so you feel refreshed and provides sleep analytics so you can maintain that fully rested feeling throughout the day.

Your answer to the second question should show a little less certainty unless you have a study to link to. I think the original commenter gets that you're just waking up a little earlier, but consistently doing that every day isn't natural. Sure, neither are alarm clocks in general, but there are probably studies about those. This is a special case of alarm clock that could, in theory, have different long-term effects.

There are probably legal issues with your claim as well. I'd just say that it's very unlikely to have adverse effects instead of "it is completely free of adverse affects".

I agree that it is not a good idea to make blanket statements. I have edited my original comment.

The WakeMate wakes you similarly to how you would wake if you did not set an alarm. That is why it is very unlikely to have adverse effects.

Regarding your comment: "I think the original commenter gets that you're just waking up a little earlier, but consistently doing that every day isn't natural." It may just be because I'm familiar with the product but it doesn't seem to me that setting your alarm for 9:00am and waking at 8:55am can be construed as unnatural.

If the product works really, really well and users end up waking up at the optimal time the vast majority of the time, that may (or may not) be different from the conditions in which we evolved and the various adaptations we've made since then that are better studied. It could have some sort of adverse effect. It's very unlikely.

What is the confidence interval for the size of the effect that wakemate produces on percieved grogginess vs waking without wakemate?

What is the size of the effect in the research?

Kinda going off the rails here. We get it: WakeMate is not rigorous peer-reviewed science.

I disagree. He makes two unsupported claims that reek of cargo-culting:

"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.

Sleep scientist here. Actigrams based on 3way accelerometers are very common to measure sleep in a very non invasive way and they give a resolution good enough for having an idea of sleep amount and even roughly sleep pattern. I have no idea how well wakemate works, I would love to try of course (wink).

The research-grade equivalent of wakemate is called actiwatch ( http://actiwatch.respironics.com/ ) and it costs a lot more.

"If it makes me feel good just after waking up for an hour or so, then is it really that useful?"

If I retain my daytime alertness, I think so :) Morning grogginess is pretty much the worst part of my day and I think $60 to make it go away is a pretty good deal.