Traffic Noise & Sleep Arousal 2D: Hypnogram Dose-Response Simulator

Noise Source

Outdoor traffic level (L_Amax) 78 dB

Pass-by events per hour 10

Window / façade insulation 25 dB

Night speed ×240

Live State

Sleep stageAwake

Clock

22:00

Indoor L_Aeq

— dB

Arousals

Sleep efficiency

100%

How it works

Each passing vehicle produces a brief indoor noise peak L₁ = L_Amax − Insulation. Whether it wakes the sleeper is modelled as a logistic dose-response curve — the same functional form used in field studies of aircraft- and road-noise sleep disturbance (e.g. Basner et al.):

P(arousal) = 1 / (1 + exp(−b · (L₁ − L₅₀[stage])))
b ≈ 0.12 per dB   (steepness of the dose-response curve)
L₅₀[stage] = indoor level at which P = 50%:
  N1 (light)  → 50 dB      REM        → 52 dB
  N2          → 62 dB      N3 (deep)  → 75 dB

Deep sleep (N3) has the highest arousal threshold — the brain's thalamic gating suppresses sensory relay most strongly there — while N1 and REM are far more easily disturbed. Each pass-by event is drawn as a Poisson process at the chosen rate; a random draw against P(arousal) decides whether that event produces a micro-arousal, which resets the sleeper to a brief waking stage and interrupts the ~93-minute ultradian N1→N2→N3→REM cycle that would otherwise run through the night.

L_Amax — the peak outdoor sound level of a single pass-by, in dB(A).
Events / hour — traffic density outside the window.
Insulation — façade/window sound reduction; WHO's 2018 Environmental Noise Guidelines recommend keeping bedroom L_night below ≈40 dB.
Sleep efficiency — the fraction of elapsed night actually spent asleep rather than in an arousal.

This 2D rendition drives the exact same stage-scheduling and dose-response equations as the 3D scene, plotted directly as a scrolling hypnogram rather than a 3D bedroom — drag to pan the strip, scroll/pinch to zoom the time axis.

This is a simplified, literature-inspired teaching model, not a clinical instrument — real dose-response coefficients vary with individual sensitivity, prior sleep debt and noise spectrum.

N1 / N2 light sleep N3 deep sleep REM Arousal

Indoor now— dB

drag to pan · scroll to zoom hypnogram