Lossless soundscapes, binaural brainwave entrainment, smart alarms with wake-up challenges, and sleep tracking. Purpose-built for the night — your brain won't fight this.
Lossless FLAC audio, real-time binaural beat generation, automatic sleep tracking, and alarm failsafes. Every feature is engineered for reliability — not just aesthetics.
Rain, thunderstorms, ocean, forest, white/pink/brown noise, fan, airplane cabin, and more — all stored locally in lossless FLAC format with seamless 4-second crossfade looping. No streaming, no compression artifacts, no audible gaps.
A real-time binaural beat engine generating stereo tones at 44.1 kHz. Three manual modes — Delta (deep sleep), Theta (meditation), Alpha (relaxation) — plus IOn Flow's automatic 4-phase progression that mirrors your natural sleep cycle. Requires headphones.
Layer up to 3 sounds with independent volume sliders plus master control. Save your favorite combinations as custom presets. 6 built-in presets included — Deep Sleep, Rain Focus, Travel, Forest Escape, Storm Cozy, and Café Vibes.
Gentle wake-up with configurable fade-in or Heavy Sleeper mode. 6 challenge types: Math Burst, Memory Flash, Phrase Typing, Shake Phone, Step Counter, and Target Tap. Progressive difficulty — each snooze makes challenges 25% harder. Survives device restarts.
6 dynamic visual themes that sync to real weather via ZIP code — Clear, Deep Night, Rainy Night, Thunderstorm, Cloudy Sky, and Snowy Weather. Animated particle effects (rain, snow, lightning, stars) with smart sound recommendations based on conditions.
Sleep detection begins automatically after 5 minutes of sound playback — no manual start button. Tracks sleep duration, wake time, session type (sleep vs. nap), average trends, weekly/monthly history, and a 0–10 weekly sleep rating.
10-min micro, 20-min power, 30-min recovery, or custom duration naps. Each preset has its own optimized IOn Flow binaural beat progression. Sleep timer fades sounds and crossfades into your alarm — 30 seconds of overlap means you never wake to silence.
All 21 sounds bundled locally. Alarms, mixer, challenges, IOn Flow, and sleep tracking all work in airplane mode. No account required. Dedicated battery saver mode for overnight use. Auto Do Not Disturb integration. We collect only anonymous crash reports and feature analytics.
Choose from 21 sounds or mix up to 3 together. Nature, noise, ambient — layer them into your perfect sleep environment.
Configure a gentle wake, heavy sleeper alarm, or wake-up challenge. When it's time, sleep sounds crossfade into your alarm over 30 seconds — never silence, never jarring.
IOn Sleep runs all night on minimal battery. Ion Flow guides you through optimal sleep frequencies. Wake up refreshed.
Most sleep apps play a looping sound file and call it a night. IOn Sleep is an intelligent sleep system — it doesn't just mask noise, it actively guides your brain into deeper sleep using brainwave entrainment backed by peer-reviewed neuroscience research.
Other apps play a single binaural frequency on repeat. IOn Flow is a real-time adaptive engine — it generates stereo sine waves at 44.1 kHz and automatically progresses through four brainwave phases across your entire sleep session, mirroring your brain's natural sleep architecture.
This isn't guesswork. Brainwave entrainment — the principle that auditory stimuli at specific frequencies can influence neural oscillation patterns — is supported by decades of published research. IOn Flow also adapts to power naps, with optimized phase timing for 20, 30, and 45-minute sessions.
Enter your ZIP code and the app transforms — animated rain particles when it's raining, lightning bolts during storms, falling snowflakes in winter. Smart sound recommendations match real conditions outside.
Every sound is bundled in lossless FLAC format with seamless 4-second crossfade looping. No compression artifacts, no buffering, no internet required. Studio-quality audio all night, every night.
System-priority scheduling with a failsafe backup that fires at max vibration if the primary alarm fails. 30-second crossfade from sleep sounds into alarm — you're never exposed to silence. Survives device restarts.
Dedicated Battery Saver mode delivers ~2× battery life improvement. Foreground service with partial wake lock survives Doze mode. Manufacturer-specific guides for Samsung, Pixel, Xiaomi, OnePlus, and more.
| Design Choice | IOn Sleep | Typical Sleep Apps |
|---|---|---|
| Works in airplane mode | ✓ Fully offline core | ✕ Streaming required |
| Audio quality | Lossless FLAC, seamless crossfade | Compressed, loop gaps |
| Alarm reliability | System-priority + failsafes | App-level only |
| Sleep → alarm transition | 30s crossfade (never silence) | Abrupt cut or overlap |
| Binaural beats | Real-time adaptive engine | Pre-recorded tracks |
| Wake-up enforcement | 6 mandatory challenges | Optional / skippable |
| Privacy model | No recordings, no GPS | Varies, often opaque |
| Battery strategy | Dedicated saver mode | Minimal control |
Free to download. No account required. Just rest.
Get IOn Sleep — Free