Sleep Health
Poor sleep is not just feeling tired. It is a measurable driver of nearly every other health outcome we track.
Key takeaways
- Total hours is the least informative sleep metric you can track.
- Deep sleep drives physical repair and growth hormone release. REM drives memory and emotional regulation.
- Consumer wearables can hint at disordered breathing but cannot diagnose it, so a sleep test is what settles the question.
- Alcohol is the single most reliable way to destroy deep sleep without shortening time in bed.
Sleep health covers both how much you sleep and how well, the duration, quality, and structure of your sleep, and how that affects everything else in this list.
Sleep is not one thing to optimize, it is several. Total time asleep matters, but so does how that time breaks down between deep sleep, when the body does most of its physical repair, and REM sleep, when memory and emotional processing happen. Chronic short sleep, generally under 7 hours a night, is independently linked to cardiovascular disease, weight gain, cognitive decline, and slower recovery from everything else on this site, regardless of how well someone eats or trains.
Most people only track total hours through a fitness wearable. That misses the two things that actually explain why someone wakes up tired despite a full night in bed: how often sleep is interrupted, and whether breathing is disrupted during the night. Baseline's plan is to offer dedicated sleep testing and tracking so people can see the parts of sleep a regular wearable does not capture, not just hours logged.
Biomarkers tracked here: Total Sleep Duration, Deep Sleep, REM Sleep, Sleep Apnea Screening (AHI), HRV. Full detail on each in the Biomarker Hub below.
Sleep is structured, not uniform
A night of sleep cycles through light, deep, and REM stages roughly every 90 minutes. Deep sleep concentrates in the first half of the night and is when most growth hormone is released, tissue repair happens, and the glymphatic system clears metabolic waste from the brain. REM concentrates in the second half and handles memory consolidation and emotional processing.
Both matter, and they are lost differently. Late alcohol suppresses the first half. Cutting the night short at the alarm removes the second.
Why eight hours can still feel bad
- Fragmentation. Frequent brief arousals prevent completed cycles without registering as time awake.
- Disordered breathing. An untreated apnea-hypopnea index above 5 fragments sleep every night and is common in people who do not fit the stereotype.
- Circadian misalignment. Sleeping the right number of hours at the wrong clock time yields lower-quality sleep.
- Late alcohol. Sedation is not sleep. Deep sleep drops measurably even at modest intake.
- Elevated evening cortisol, which delays sleep onset and shallows the early night.
What to track and what it should look like
- Total sleep duration: 7.5 to 9 hours.
- Deep sleep: roughly 13 to 23% of total sleep time, with the trend mattering more than any single night.
- REM sleep: 20 to 25% of total sleep time.
- AHI: under 5 events per hour, confirmed by testing rather than estimated.
- HRV: stable or improving against your own baseline.
Where Baseline is heading
Sleep is being built out as its own pillar: dedicated testing, targeted enhancement protocols, and ongoing tracking, so the recovery window gets the same rigor as hormones and metabolism.
Until testing is available through us, the highest-yield changes remain a fixed wake time, morning light, a cool dark room, no alcohol within three hours of bed, and a provider evaluation if snoring, witnessed pauses, or morning headaches are present.
What this means for you
If you sleep eight hours and still wake tired, the issue is quality or breathing, not duration. That distinction requires testing, not a wristband.
Therapies discussed here
References
- Biomarker hub: Biometric markers
- Sleep medicine: Why sleep deserves its own pillar