Night and Day Tracker
Track Sleep Debt & Activity
About
Gain deep insights into your sleep and activity levels to optimize performance and well-being. This app provides personalized sleep scores, sleep debt tracking, and daily readiness assessments. It seamlessly integrates with Apple Watch and other HealthKit devices for comprehensive health monitoring.
What's New in Night and Day Tracker
2.1
June 13, 2026
*NEW* — Insights tab allows you to see how certain activities or behaviors affect your sleep. Choose from convenient options like "alcohol" or "late meal", or create your own! — Hitting your activity point goal will now activate a "streak". See how many weeks you can keep your streak alive, or try to beat your previous record! — The sleep tab has been revamped to show richer info at a glance. — Sleep and readiness scores and now show historical scores and trends.
MoreFAQ
What is the sleep debt tracking feature in Night and Day?
Night and Day calculates your running sleep debt balance by analyzing your sleep over the past two weeks. This feature helps you understand how much rest you owe your body, even if you don't consciously feel it.
How does Night and Day determine my daily readiness score?
Your readiness score is a comprehensive assessment that combines your sleep quality, heart rate variability (HRV), resting heart rate, accumulated sleep debt, and recent activity levels to indicate your body's preparedness for performance.
Does Night and Day require a subscription?
No, Night and Day does not require a subscription. The app is available as a one-time download and can be used forever without ongoing fees.
What devices does Night and Day integrate with?
Night and Day seamlessly integrates with Apple Watch, Oura Ring, and any other HealthKit-compatible tracker, consolidating all your health data in one convenient location.
How does Night and Day ensure user privacy?
Night and Day prioritizes privacy by processing all your health data locally on your iPhone using Apple's secure HealthKit framework. Your sensitive health information never leaves your device.
What is the scientific basis for Night and Day's algorithms?
The app's algorithms are built upon peer-reviewed sleep and exercise science, drawing from research in sleep medicine, sports science, and circadian biology to provide accurate and reliable insights.
How does Night and Day track activity points?
You earn points for every minute your heart rate elevates during exercise and daily activities. Light activity earns 1 point per minute, while vigorous activity earns 2x points, helping you aim for the WHO-recommended 150 points weekly.
What age rating does Night and Day have?
Night and Day has an age rating of 4+, making it suitable for a wide range of users interested in health and fitness tracking.