Dutch Summer/Winter Time Simulation

Netherlands · time-zone simulation UTC versus CET With and without daylight saving time

This simulation compares four time regimes for the Netherlands: UTC, UTC with daylight saving time, CET, and CET with daylight saving time. The comparison is based on solar noon, sunrise, sunset, and how much daylight falls within your waking hours.

Working assumption: solar positions are approximated using a standard astronomical method. This page therefore mainly shows the structural trade-offs: astronomical accuracy versus later evenings and darker mornings.

Reference point

Latitude

Longitude

Longitude is particularly important in the Netherlands: the farther east you go, the less logical UTC becomes.

Daily comparison

The daily chart shows how the same astronomical day appears on the clock in each scenario.

Year

The annual summary covers every day of this year. Scenarios with daylight saving time use the European rule.

Schedule profile

Based on the 2025 National Bedtime Study. The age profiles combine the bedtime distribution from the adult scatter plot with the reported sleep duration for each age group; wake-up time therefore remains a model-derived value rather than a published group average.

Source: Smulders 2025

Awake from: 07:00 Bedtime: 23:00

This affects the social score: which regime moves daylight into your active hours most effectively? Adjust these sliders if your schedule differs from the study profile.

Morning window: 3 hours Evening window: 4 hours

These controls reveal the value of bright mornings and bright evenings.

Daily chart

waking hours daylight solar noon daylight saving time active

Annual summary

Conclusions from this simulation

Comparison table

Criteria	Best	Why

How to read this

Astronomically best means that solar noon is closest to 12:00 on the clock. Socially best means that the most daylight falls within the configured waking hours. A system with daylight saving time often gains evening light, but usually loses morning light and astronomical accuracy.

The simulation does not claim that one answer is normatively required. It shows the underlying trade-off: UTC aligns more closely with the sun; CET, and especially CET with daylight saving time, move daylight later on the clock, which is often more convenient in the evening but less favourable for morning light.

Study input: the default schedule is derived from the 2025 National Bedtime Study. This study of 2,400 adults reports an average sleep duration of 6 hours and 56 minutes, with separate figures for ages 18–34, 35–49, 50–64, and 65+. For these age profiles, this page uses the bedtime distribution from the adult scatter plot; wake-up time is then explicitly derived from sleep duration and time in bed, rather than copied from a published survey average.