1. Sleep Stages (Deep and REM)
Why it matters: Sleep isn't just about duration; it's about quality. Deep sleep is crucial for physical restoration—tissue repair, muscle growth, and immune function. REM (Rapid Eye Movement) sleep is essential for cognitive functions like memory consolidation,
learning, and emotional processing. If you're waking up tired despite getting eight hours, poor-quality sleep stages are likely the culprit. Success here means feeling physically and mentally restored each morning. How to track it: Modern wearables are your best friend here. Devices like the Oura Ring, WHOOP strap, and newer versions of the Apple Watch and Fitbit use sensors to estimate your time spent in each sleep stage. Look for trends over time rather than obsessing over a single night's data.
2. Heart Rate Variability (HRV)
Why it matters: HRV measures the variation in time between your heartbeats. A higher HRV is generally a sign that your autonomic nervous system is balanced and resilient, capable of shifting gears between stress (fight-or-flight) and rest (rest-and-digest). It's a powerful proxy for your recovery, stress levels, and overall readiness to perform. A consistently low HRV can be an early warning that you're overtrained, stressed, or getting sick.
How to track it: This metric is a staple of premium wearables. WHOOP, Oura, and Garmin watches excel at tracking HRV, typically taking a measurement while you sleep to establish a personal baseline. The goal is to keep your HRV within or above your normal range.
3. Resting Heart Rate (RHR)
Why it matters: Your resting heart rate is a fundamental measure of cardiovascular fitness. Generally, a lower RHR indicates a more efficient heart muscle, as it needs fewer beats to circulate blood. Tracking your RHR over time can show you how your fitness is improving. A sudden, unexplained spike in your RHR can also be a sign of impending illness, dehydration, or high stress.
How to track it: Almost any fitness tracker or smartwatch can accurately measure RHR, usually by taking readings overnight. The key is to look at the long-term trend. As your cardiovascular health improves through exercise, you should see a gradual decrease in your average RHR.
4. Blood Glucose Levels
Why it matters: You don't need to have diabetes to benefit from monitoring your glucose. Your energy levels, mood, and cognitive focus are all tied to how your body manages blood sugar. Large spikes and crashes after meals can lead to that classic afternoon slump, brain fog, and cravings. The goal of tracking is to understand which foods and habits keep your glucose levels stable, promoting sustained energy and metabolic health.
How to track it: Continuous Glucose Monitors (CGMs), once only for diabetics, are now used by biohackers. Companies like Levels and Nutrisense pair a CGM with an app to provide real-time feedback on how your body responds to meals, exercise, and stress. A less invasive option is using a standard finger-prick glucometer to test your fasting glucose and your levels after specific meals.
5. Key Lipid Panel Markers
Why it matters: This is a classic blood test that provides critical insight into your cardiovascular and metabolic health. While a doctor will look at total cholesterol, biohackers often dig deeper into the ratios and particle numbers. Key markers to understand include HDL ("good" cholesterol), LDL ("bad" cholesterol), and triglycerides. Newer tests also measure ApoB, a protein on LDL particles that is considered a more accurate predictor of cardiovascular risk than LDL alone.
How to track it: This requires a blood test ordered by a physician or through direct-to-consumer lab services like InsideTracker or QuestDirect. It's not something you track daily, but checking in annually or semi-annually provides a vital long-term health benchmark.
6. Vitamin D and Magnesium Levels
Why it matters: These two micronutrients are power players in your overall well-being. Vitamin D is a hormone that impacts everything from immune function and mood to bone health. Magnesium is a cofactor in over 300 enzymatic reactions, influencing muscle function, nerve transmission, sleep quality, and blood sugar control. Deficiencies in either are incredibly common and can contribute to fatigue, poor sleep, and a weakened immune system.
How to track it: Simple blood tests can reveal your levels. A standard Vitamin D (25-hydroxy) test is common, while an RBC Magnesium test is often considered more accurate for magnesium status than a standard serum test. You can request these from your doctor or through private lab services.
