My Oura biofeedback ring is telling me a lot about my sleep patterns. Having used a CPAP for many years, I am used to being told in the morning about how many hours I “slept” the previous night and a few statistics about my breathing and heart action during the night. Generally, since I’ve never had a formal diagnosis of Obstructive Sleep Apnea (OSA), it’s not surprising that the follow-on statistics have always been pretty solid and smiley-faced (the icon used on the CPAP machine readout). But what this information has never told me about is the quality of my sleep, and that’s where Oura is filling in some of the blanks.
In general, I do not have a problem getting to sleep, but rather, my issue tends to e staying asleep. Both are types of insomnia, but they point to different underlying patterns and often different causes. With trouble falling asleep (sleep-onset insomnia), you lie awake for a long stretch (often 20-30+ minutes) before drifting off, often thinking about all the things that are troubling you from the day or about the next day. The common causes are racing thoughts/anxiety, caffeine too late in the day, irregular bedtime, delayed circadian rhythm (“night owl” tendency), screen/blue light exposure before bed or restless legs syndrome. As for trouble staying asleep (sleep-maintenance insomnia), you tend to fall asleep fine but wake up one or more times during the night, or wake too early and can’t get back to sleep. The common causes are sleep apnea, needing to urinate frequently (enlarged prostate, overactive bladder), pain conditions (usually joint or muscle aches and pains), alcohol (helps you fall asleep but fragments sleep later), stress hormones spiking overnight, aging (sleep naturally gets lighter and more fragmented) and/or depression (early morning waking is a classic sign). Sleep-onset issues often point toward behavioral/circadian causes and respond well to things like consistent sleep timing, light exposure management, and reducing pre-bed stimulation. Sleep-maintenance issues more often point toward a physiological disruptor (apnea, pain, hormonal, medication side effects) and may need a different workup, for example, a sleep study if snoring or gasping is involved. That’s exactly what brought about my use of a CPAP even though there was no clear apnea present.
Sleep apnea prevalence has been rising steadily in the U.S. and is now quite high. A recent 2024 estimate put OSA at roughly 32% of US adults aged 20 and older, representing over 83 million people. That’s up sharply from around 26% of adults aged 30-70 just a decade or so earlier. Projections suggest it’ll keep climbing, and researchers expect nearly 77 million US adults to have OSA by 2050, a roughly 35% relative increase from 2020. As for why it’s rising…the increase over the last two decades is mostly attributed to rising obesity rates, since excess weight (especially around the neck/airway) is a major risk factor as well as the aging population and increasing BMI of that group. It’s not just that more people have it, but, as with many conditions, we’re also diagnosing it more. Better awareness, more home sleep testing, and wider CPAP prescribing mean cases that used to go unnoticed (especially mild cases) are getting caught. One VA study found severe OSA cases dropped by half while mild OSA cases increased seven-fold over about a decade, suggesting some of the “rise” is really a rise in detection, not just true prevalence, though the obesity-driven increase in real cases is well documented too. In my case, the CPAP has worked well in solving the majority of the issue and now that I’ve lost weight and my BMI is down almost to normal levels, I can sleep just fine without the CPAP. But what about that quality of sleep issue?
This morning I awoke at 5:40am, having gone to bed with no difficulty at 10:49pm. That’s 6 hours and 49 minutes in bed, which is perhaps a little lighter than I would like, but no so bad. However, Oura tells me that I only got 4 hours and 32 minutes of sleep during that stint in bed and under the covers. That gave me a sleep efficiency score of 66%, which Oura doesn’t even give a “Fair” score to, but rather says “Needs attention”. Oura wants me to get to 85% efficiency. It also tells me that I have accumulated a sleep debt of 12 hours and 50 minutes, which is quite high. It tells me that I need 6 hours and 41 minutes and am getting, on average, two hours too little. It is not unusual for me to wake up once in the night to relieve my bladder, but that is preferably after a 3-4 hour span of restful sleep. While I get most of my deep sleep during that first period of rest, my REM sleep. REM and deep sleep (slow-wave sleep) serve pretty different purposes, even though both are essential. Two sleep provides physical restoration like tissue repair, muscle growth and immune system strengthening. It also serves to consolidate declarative memory, when facts, information and things you consciously learned are stored. By contrast, REM sleep, which is typically more concentrated in the second half of the night, is when brain activity looks almost like being awake and when most vivid dreaming happens. This time is about consolidating procedural and emotional memory, things like skills, motor learning, and processing emotional experiences. This is thought to help with creative problem-solving, allowing us to make novel connections between ideas. It plays a role in emotional regulation, processing difficult experiences so they feel less raw the next day. Your body is essentially paralyzed during REM (to prevent you from acting out dreams), while your brain is highly active. Deep sleep deprivation tends to leave you physically run-down, achy and immune-compromised, whereas REM deprivation tends to hit emotional regulation and cognitive flexibility harder, making us get irritable, having trouble learning new skills, and struggling with emotional processing.
What all of this tells me is that all my good physical work and weight loss is doing a decent job of revitalizing my body, but meanwhile, I seem to be losing ground in my emotional stability. It turns out that insufficient sleep works against weight loss so that’s an interesting interaction to understand. Sleep deprivation increases ghrelin (the hormone that signals hunger) and decreases leptin (the hormone that signals fullness). The net effect is that you feel hungrier and less satisfied after eating, even if calorie intake hasn’t changed. Poor sleep increases cravings for high-calorie, high-carb foods, which is likely tied to changes in reward-processing regions of the brain and studies show that people eat more overall (not just different foods) when sleep-deprived, often several hundred extra calories a day. In calorie-restricted conditions like mine, sleep-deprived people lose more muscle mass and less fat mass compared to well-rested people losing the same amount of weight. One well-cited study found this split shifted dramatically with just 5.5 hours of sleep vs 8.5 hours. This matters because muscle is metabolically active tissue and losing more of it than necessary can slow metabolism over time. Poor sleep also raises cortisol, which is linked to abdominal fat storage. The bottom line is that diet and exercise still matter most, but sleep isn’t a neutral bystander. Chronic short sleep (routinely under 6-7 hours) can undermine the results of an otherwise solid weight loss effort by making you hungrier, pushing you toward worse food choices, and shifting what you lose away from fat and toward muscle. I guess I better force myself to stay under the blanket a bit longer…