Block blue light after sunset

The body’s circadian system reads light as a clock signal. Bright blue-spectrum light after dark tells the brain it’s still daytime, suppressing the melatonin release that should be starting an hour or two before bed. Most evening screen use is precisely this signal, on full strength, until lights-out.

What it looks like

From sunset (or roughly 7pm in winter) onward, screens go warm. Most operating systems have a built-in “night shift” or “night mode.” Set it to schedule with sunset; you’ll forget about it after a week.

If you wear glasses, blue-light-blocking lenses are an alternative for the evening hours. They look slightly amber but the eye adapts within a minute. For phones, an app-level filter on top of the OS night mode is more aggressive and worth running if sleep is the priority.

Why it works

Blue-spectrum light suppresses melatonin more reliably than other wavelengths. Reducing it from sunset onward lets the natural pre-sleep cascade start on time. Most people who run this for thirty days notice they get sleepy earlier, sometimes by a full hour, without changing anything else.

It also pairs well with no-screens-after-9: the warm-tone shift starts the wind-down even if you’re still on screens, and the no-screens cutoff seals it.

Common pitfalls

The first pitfall is leaving it manual. A schedule that triggers at sunset runs by itself; a manual toggle doesn’t. Configure once.

The second is treating it as the whole sleep intervention. Blue light is one input. Caffeine timing, room temperature, and a consistent bedtime do most of the work. The blue-light shift is the cheapest add-on.

The third is overdoing the orange. Some people set the filter so warm that everything looks like a sunset. The eye finds it tiring. Moderate warmth is enough.

A 30-day cycle suggestion

Thirty days, daily. Success criteria: 28 of 30 evenings, screens warm from sunset onward.

Exit condition: when the warm shift happens automatically and sleep onset has visibly eased.