While there are many things that can cause poor sleep (I’ve written about several here), nighttime breathing issues are one of the less obvious ones. When it comes to nighttime breathing issues, there is the obvious obstructive sleep apnea (OSA) and the less obvious upper airway resistance syndrome (UARS). There’s also central sleep apnea, where your brain basically isn’t telling your lungs to breathe, but since that is comparatively rare, I won’t speak to that here.
When it comes to OSA and UARS, the issue can either be simple (your neck is too thick—say, from obesity—and when you lose weight the problem goes away) or more subtle, as when the issue is more structural. OSA is when you literally stop breathing to the point where your blood oxygen levels drop X number of times per hour, whereas UARS is a situation where you’re simply working harder to breathe than you ought to be. Though UARS is less severe in terms of the pathology, the daytime symptoms are often the same.
If you feel your sleep isn’t as refreshing as it should be, the first step would be a sleep study. But rather than bother with going to a sleep lab (which is theoretically more accurate, but also way more of a hassle), you can order a simple at-home version. I’ve done a few with a company called iSleep. They send you a device called the WatchPAT One, you download an app, you pop the device on before you go to bed, and in the morning you throw the device away while your data gets sent to a tech who writes up a report. Once you know what’s up, you can begin addressing the issue.
As for solutions, they are myriad, from positional therapy (aka sleeping on your side vs your back) to CPAP to myofunctional therapy to surgeries (The Breathe Institute in Los Angeles specializes in all manner of solutions). But that’s far above my pay grade. For now, I’d recommend this podcast about nighttime breathing for some of the basic groundwork.