What is an upgrade over the original is the ability to wave your hand to turn off standard alarms and timers—handy when there's no Snooze button to smash. You'll need to set up these smart gestures beforehand, but it's worthwhile.
It's nice using the Nest Hub to turn off the lights without lifting a finger, but the big new feature here is Sleep Sensing. It's free for the first year but will eventually require a subscription. There's no word on what it will cost, but it may be a perk under Fitbit Premium. (Google owns Fitbit as of January 2021).
Sleep Sensing is powered by Google's Soli chip, which uses radar to visualize what's in front of it. This is what enables the smart display to recognize your hand wave to pause alarms. It debuted on other devices like the Google Pixel 4, but this is the first time Google is utilizing it to measure sleep. Once you've positioned the Nest Hub on your nightstand to face your side of the bed, it will detect when you've gotten under the covers and fallen asleep. (It only works for the person closest to the display, so, no, it won't track your partner's sleep.)
It monitors your respiratory rate while sleeping, and if it's consistently not in a recommended zone, flag it to your physician, as problems can range from heartburn to sleep apnea. It can also track other behaviors like coughing and snoring. The latter made me face the harsh reality that every so often I do let out a snore, which I refused to believe until the screen presented the evidence to my face. (I'm blaming it on my congestion.) When you wake up in the morning, you'll get a basic overview of the night before with some advice, like getting into bed later or earlier.
But Google seems to have trouble tracking exactly when I'm falling asleep. I'm often in bed for at least an hour scrolling through TikTok or playing Solitaire. Since I'm not actually asleep, each morning Google recommends I get into bed later than I did the night before. If you usually spend some time reading, watching TV, or TikToking on your phone before shutting your eyes, you might want to turn the screen away until you're ready.
Sleep Sensing also tends to pick up my cat's afternoon snoozes, though the tracking doesn't last long enough to mess with my own sleep data. More problematic is that it doesn't take naps into account, so when I take a 45-minute rest in the afternoon, it says I got into bed too early for the night. The software feels like it's in beta—probably why it's free for the first year as Google fine-tunes the experience.
As is the case with most health-tracking tech products, the Nest Hub is not a replacement for visiting a sleep physician, especially if you suspect you have sleep apnea or any serious sleep condition. It offers minor suggestions, like lowering the temperature in your bedroom or blocking out more light to improve your sleep, but it can't make a medical diagnosis.