Here is a smart wearable device that sits on your wrist and monitors blood oxygen saturation level. The ViATOM Blood Oxygen Saturation Monitor has a soft silicone ring sensor that is comfortable to wear. It also features adjustable vibration that wakes you up with a nudge when your blood oxygen saturation falls below your defined level.
The free PC software lets you export sleep reports in CSV and PDF format. The device is USB rechargeable and lasts 16 hours.