Do you need a wearable to track your sleep?

No, but they answer different questions, and knowing which question you have saves you money.

What a wearable is better at

Anything touching your body. A watch or ring sits against your skin, so it can track heart rate, heart rate variability, movement, and on some devices blood oxygen and temperature. That combination gives a much better estimate of when you fell asleep, how restless you were, and a more credible stab at sleep stages.

If your question is how much did I actually sleep, a wearable is the better instrument.

What a phone is better at

Anything you could hear from across the room. A wearable knows your wrist moved; it does not know a truck went past, that your partner got up at 2 a.m., or that you talked in your sleep for eleven seconds. It certainly cannot let you listen to it in the morning.

If your question is what is happening in my bedroom and what noise am I making, the phone is the better instrument, and it is the one already on your nightstand.

Together they are better than either

These are complementary rather than competing. SoundSleep will read sleep stages your Apple Watch already recorded, via Apple Health, and lay your sound events over them. That is when the interesting question becomes answerable: not just “I woke at 3:10” but “I woke at 3:10, and the dog barked at 3:09.” A watch alone gives you the awakening. A phone alone gives you the bark. Together you get the cause.

If you are buying nothing

Start with the phone. It costs you nothing, it needs no charging routine, and for the specific problems of snoring, sleep talking and a noisy bedroom it is the right tool rather than a compromise. Add a wearable later if you find yourself wanting the body-side numbers.

SoundSleep is not a medical device and nothing here is medical advice. If your sleep worries you, talk to a doctor.