1. Overview

The Sleep Timer in SonicSyncSail provides a gradual, calming way for listeners to drift into rest while enjoying their favorite music. It is accessible directly from the Now Playing screen via the sleep timer icon. Once tapped, a dedicated dialog appears, offering preset durations, custom timing, and a perception-aware volume fade system.

Unlike traditional sleep timers that abruptly stop music, SonicSyncSail uses a sophisticated fade algorithm designed to gently guide the mind toward relaxation before playback is paused.

2. Purpose

The Sleep Timer is intended as a tool for mental unwind—supporting reflection, calming routines, and sleep preparation. It aims to reduce sensory load gradually, allowing listeners to transition into restful states without sudden breaks in sound.

The system is designed so that users can:

• Fall asleep naturally while listening to music
• Experience a gentle fade into silence rather than abrupt stops
• Maintain system-level sounds such as calls or notifications
• Sustain mood coherence as the audio gradually softens

3. Sleep Timer UI Structure

3.1 Preset Durations

The dialog provides three quick-access presets:

• 15 minutes
• 30 minutes
• 60 minutes

3.2 Custom Duration Slider

• Minimum: 5 minutes
• Maximum: 180 minutes
• Default value: 30 minutes

3.3 Volume Fade Slider

• Minimum fade: 5%
• Maximum fade: 50%
• Default fade value: 35%

3.4 Start Button

Activates the timer and closes the dialog. All fade parameters and timing are pre-calculated when the timer begins.

4. Dynamic Running State

When the sleep timer is active, the dialog automatically transitions into a minimal “running” interface:

• Presets and sliders collapse
• A live countdown timer appears
• The interface displays “XX:YY remaining”
• A Cancel Timer button becomes available

Countdown updates every second in real time.

5. Volume Fade Logic

The Sleep Timer incorporates a perception-aware volume fade designed to be gentle, gradual, and psychologically natural. The fade begins when the remaining time reaches the user’s fade threshold percentage. For example:

If duration = 120 minutes and fade start = 27%, volume fade begins when approximately 33 minutes remain.

5.1 Multi-Stage Fade Design

The fade curve operates across several subtle phases:

• Initial Stability: Volume decreases extremely slowly at first, preserving immersion.
• Mid-Stage Descent: Volume shifts into a soft fall pattern, still nearly imperceptible.
• Late-Stage Narrowing: Volume reduction becomes slightly more pronounced, preparing the mind for the final transition to silence.
• Final Quiet: Music reaches near silence before pausing completely.

Each micro-step is intentionally minor and time-spread so listeners do not consciously detect volume drops.

5.2 Fade Applies Only to Music

The Sleep Timer adjusts only the app playback volume, not the device’s system volume. This ensures:

• Calls remain audible
• Notifications play as expected
• Other apps are not affected

6. Why the Fade System Matters

The fade system is crafted as a sleep preparation tool rather than a simple volume drop. SonicSyncSail recognizes how human auditory perception responds to sound reduction:

6.1 Gradual Adaptation

The human brain adapts to decreasing sound more slowly than to increasing sound. Sudden decreases can trigger micro-arousals. The Sleep Timer avoids this with ultra-smooth transitions.

6.2 Sleep-Friendly Psychology

The fade subtly narrows the mind’s attention, encouraging:

• Eye closure
• Reduced sensory stimulation
• A gentle inward mental shift
• Lower cognitive activity

6.3 Smooth Descent Into Silence

When the music naturally fades to silence, the listener’s mind interprets it as a seamless continuation of relaxation, not an interruption.

For best results, users are encouraged to close their eyes once the timer begins and follow the sound as it gently softens.

7. Behavior When Timer Ends

When the timer reaches zero:

• Music playback pauses automatically
• App volume resets to normal
• The timer clears itself

8. Canceling the Timer

If the user presses “Cancel Timer,” the following occur immediately:

• Countdown stops
• Volume restores to its standard level
• Fade logic is discarded

9. App Closure Handling

If the user closes the app before the timer ends, the system interprets this as a user-initiated stop. Therefore:

• Timer cancels itself automatically
• No fade continues in the background
• Volume resets to normal

10. Edge Cases & Safeguards

• Fade applies only to SonicSyncSail playback
• System sounds remain unaffected
• Volume instantly restored when timer is cancelled
• Fade percentage capped at 50% for safety
• Duration capped at 180 minutes
• Fade does not interrupt PulseSync transitions

11. Known Limitations

• Timer may reset if app is force-stopped by the operating system
• No advanced multi-phase fade curves at present
• No “fade to ambient” mode currently available