Wearable-Free Energy Tracking
Energy and Sleep Tracking, No Wearable Required
You should not need a ring, band or watch to know whether today is a high-output day or a recovery day. MaxDex estimates sleep and energy from the phone you already carry — and is explicit about where that estimate stops.
How does MaxDex track sleep without a wearable?
Short answer
It fuses three independent signals — gaps in screen interaction, operating-system sleep classification events, and accelerometer stillness windows — then scores the resulting episode for efficiency, disturbance and estimated awake minutes.
Running three detectors rather than one is the core design choice, because each fails differently: interaction gaps break during a long film, classification events are unavailable on some devices, and stillness misreads a phone left on a desk. The engine picks the best-supported candidate instead of trusting any single signal.
Uncertain nights are handled honestly rather than confidently. A low-confidence reading is blended toward your personal sleep baseline instead of being allowed to swing your score, so one noisy detection does not distort a week of data. The full algorithm is published in how phone-only sleep detection works.
How accurate is phone-only sleep tracking?
Short answer
Good enough for planning, not good enough for diagnosis. It estimates when you slept and roughly how disturbed it was. It cannot measure heart rate, HRV or blood oxygen, and it does not produce sleep staging at all.
Reviews of consumer sleep technology have found that wrist-worn devices perform reasonably on total sleep duration while performing variably on sleep staging. MaxDex focuses on practical duration and timing trends from phone signals to inform your daily plan without requiring wearable hardware.
What a phone does offer is that it is already on your nightstand, charged, every night. Consistency of measurement has real value that head-to-head accuracy comparisons tend to miss.
Sources
- de Zambotti, Cellini, Goldstone, Colrain & Baker (2019). Wearable Sleep Technology in Clinical and Research Settings. — Medicine & Science in Sports & Exercise
Related
What actually goes into the energy score?
Short answer
Seven weighted drivers: circadian rhythm, homeostatic sleep pressure, meal response, training load, movement, cognitive load and sleep inertia. They are summed into an arousal value and mapped through a sigmoid onto 0-100.
Sleep pressure carries the heaviest weight, at 1.5 against 1.0 for the other drivers. That reflects the evidence that sleep loss has the largest and most reliable effect on next-day functioning — and, importantly, that people badly underestimate their own impairment while it is happening.
Every constant is published at how the Energy Index is calculated, including the ones that make the model look worse.
Why does the score dip in the afternoon?
Short answer
Because the post-lunch dip is circadian, not nutritional. It is modelled as a separate Gaussian centred around 2:30pm, independent of whether you ate — though a fast-carbohydrate lunch does deepen it.
The dip appears in controlled studies even when participants skip lunch and cannot tell the time. Modelling it as a property of the clock rather than of the meal is what lets the planner stop scheduling your hardest work into a window your physiology has already spoken for.
Meals do interact with it. The metabolic driver predicts a crash risk and a time-to-peak-drag when you log a meal, so the suggestion to take a short walk arrives before the dip rather than during it.
Sources
- Monk, T. H. (2005). The post-lunch dip in performance. — Clinics in Sports Medicine
What does the score actually change?
Short answer
It changes what the planner suggests and what Max raises on a call. High-capacity windows get protected for demanding work; low-capacity ones get admin, recovery, or a smaller plan — not a guilt trip.
A readiness number is only worth having if it changes a decision. That is the gap the hardware brands leave open: they sell the metric and leave the scheduling to you. Here the metric feeds the plan and the timing of the check-in call directly.
Frequently asked questions
Do I need a wearable to track sleep in MaxDex?
Is phone-only sleep tracking as accurate as an Oura ring?
Does MaxDex measure heart rate or HRV?
Does the phone need to be on the bed or under my pillow?
2 more questions
What happens if I forget my phone overnight?
Does it work if I do shift work or sleep during the day?
Last reviewed August 28, 2026 by the MaxDex Services team. How we research and review this.