Heart Rate Variability Horizon

import matplotlib.pyplot as plt
import numpy as np

COLORS = {
    'high': ['#4d1a30', '#8a3050', '#F5276C'],
    'low': ['#1a3d4d', '#2d6070', '#27F5B0'],
    'background': '#0a0a0f',
    'text': '#ffffff',
}

np.random.seed(789)
seconds = np.arange(0, 300)  # 5 minutes
hrv = 50 + 20 * np.sin(seconds * 0.05) + np.random.normal(0, 10, len(seconds))
hrv_centered = hrv - 50

fig, ax = plt.subplots(figsize=(14, 3), facecolor=COLORS['background'])
ax.set_facecolor(COLORS['background'])

band = 15

ax.fill_between(seconds, 0, np.clip(hrv_centered, 0, band), color=COLORS['low'][0])
ax.fill_between(seconds, 0, np.clip(hrv_centered - band, 0, band), color=COLORS['low'][1])
ax.fill_between(seconds, 0, np.clip(hrv_centered - 2*band, 0, band), color=COLORS['low'][2])

ax.fill_between(seconds, 0, np.clip(hrv_centered, -band, 0), color=COLORS['high'][0])
ax.fill_between(seconds, 0, np.clip(hrv_centered + band, -band, 0), color=COLORS['high'][1])
ax.fill_between(seconds, 0, np.clip(hrv_centered + 2*band, -band, 0), color=COLORS['high'][2])

ax.axhline(0, color='#555555', linewidth=0.5)
ax.set_xlim(0, 299)
ax.set_ylim(-20, 20)

ax.set_title('Heart Rate Variability (RMSSD)', color=COLORS['text'], fontsize=12, fontweight='bold', pad=10)
ax.set_xlabel('Time (seconds)', color=COLORS['text'], fontsize=10)
ax.set_ylabel('HRV (ms)', color='white', fontsize=10)

for spine in ax.spines.values():
    spine.set_visible(False)
ax.tick_params(colors=COLORS['text'], labelsize=9)

plt.tight_layout()
plt.show()