Most of what I read about Temple is about something other than the device. Some people treat it as a brain scanner, a medical test, or the answer to recovery tracking. Others dismiss it as a smartwatch worn on the head. I think both readings name something real and leave something out, and since I've already written about ordering it, I should say where I stand.
I pre-ordered it. I haven't worn it, and I have no results from it. This is not a review. Why I ordered it, and what the early studies show, are in the first essay, and I won't go through them again. This piece is about the distance between the object and the talk around it.
What it is
Temple is an optical wearable that sits at the side of the head. It's made by Temple Private Limited, a company registered in India. Its homepage leads with a score called Entropy, which it describes as how hard the body is working to shed heat.
At rest, the homepage says, Entropy shows the load the body carries across nine systems: thermal, immune, digestive, cognitive, emotional, pharmacological, postural, reproductive and recovery. A low reading at rest is called Resting Entropy. The highest Entropy sustained near maximum heart rate is called Entropy Max. The two combine into Span, which the site presents as one number for how well the body is doing across a wide range of systems.
The other output is BrainFlow. In Temple's own preprint, it is a proprietary, dimensionless index, intended as a proxy for relative changes in blood flow in the brain.
It helps me to keep three things apart: the sensor, the score and the name. The sensor is optical hardware at the temple. The score is what Temple's software computes from the signal, and the company itself calls BrainFlow proprietary. The name is what the score is called. Most people meet the name first.
By its own terms of use, Temple is a wellness product. The data is "for general wellness and informational purposes only." The terms say the device is not a medical device, that the company makes no warranty about the accuracy or reliability of the data, and that the accuracy isn't meant to match professional medical or scientific measurement equipment.
So the object is a consumer wellness wearable, and a bet that the head is a better place to measure than the wrist. I haven't validated that bet. I'm not in a position to.
What it isn't
It isn't a brain scanner. A sensor near the brain is not reading the brain, and light sent in at the temple also passes through tissue outside the skull. The word "proxy" in the company's own description matters. A proxy for relative change is not a measurement of absolute blood flow, and the same preprint says further studies are needed to establish how specific the signal is to the brain.
Nor is it, as far as I can tell, simply a watch worn on the head. That reading has something to it. A watch is optical sensing too, and a sensor that stays in one place may well be more consistent than a strap that shifts through the day. But consistent isn't the same as meaningful, and Temple's claims rest on the processing, not the hardware. I haven't seen anyone outside the company test that processing yet. Until someone does, "it's just a watch" and "it reads the brain" are both confident claims about processing I can't see.
Look at how the names work. Say BrainFlow and you picture a brain with blood moving through it. Say Entropy, then list nine systems, and you picture the whole body on one dial. The picture arrives before the evidence does.
That is why I don't take Span as a verified readout of immune function, digestion, mood, cognition and recovery in one number, even though the homepage describes it that way. None of the research I've read tests that number against those systems. A description that lists nine systems tells me what the company says the score reflects. It doesn't tell me what the score measured.
It isn't proof that I'll get better training advice than a wrist strap gives me. I don't know, and I won't know until I've worn it. Until then I won't treat Entropy, Span or BrainFlow as permission to train, or as a reason to ignore how I feel.
And it isn't something I can speak about as a user. When I've used it, I'll write about that.
I'm interested, and I'm not convinced yet. For now, that's the most I can say honestly.