Chickens Lay Bigger Eggs on a 28-Hour Day

Somewhere in a research facility, chickens are living on Mars time. By manipulating light cycles to create artificial 28-hour "days," scientists discovered something remarkable: hens lay significantly bigger eggs with noticeably stronger shells.

This isn't science fiction—it's ahemeral lighting, a technique used in poultry facilities across Europe and the United States. The term "ahemeral" simply means "not based on a 24-hour cycle," and it turns out chickens don't actually care what Earth's rotation schedule is.

Why Longer Days Make Bigger Eggs

A chicken's reproductive system operates on an internal clock that responds to light exposure. On a standard 24-hour cycle, hens typically need about 26 hours to fully form an egg—slightly longer than our day. This creates a natural lag where eggs get laid progressively later each day until eventually a hen "skips" a day.

When researchers extended the light-dark cycle to 28 hours, something clicked. The hens' bodies had more time to complete egg formation without rushing. Studies found that eggs produced under 28-hour cycles were heavier, with measurably thicker shells compared to 24-hour controls. Some research showed shell thickness increased consistently as cycle lengths stretched from 23 to 30 hours.

The Trade-off

There's no free lunch in egg production. While 28-hour cycles create premium eggs, hens lay fewer of them overall—simply because they're living fewer "days" per week. Seven Earth days contain only six 28-hour chicken days.

But here's where it gets clever: the reduction in quantity is offset by improvements in quality. For older hens whose egg production naturally declines, ahemeral lighting extends their productive lifespan. Instead of culling birds whose shells have gotten too thin, farmers can switch to extended light cycles and keep them laying sellable eggs.

Circadian Hacking for Profit

Modern commercial operations use environmentally controlled buildings where chickens never see actual sunlight. In these facilities, "day" and "night" are whatever the timer says they are. Farmers can program 26-hour cycles, 28-hour cycles, or experiment with other lengths to optimize for different goals.

• 24-hour cycles: Maximum egg quantity, standard quality
• 26-28 hour cycles: Reduced quantity, larger eggs, stronger shells
• 27-30 hour cycles: Largest eggs, lowest production rate

The practice raises interesting questions about animal welfare and natural rhythms, but from a purely biological standpoint, chickens adapt surprisingly well. Their circadian clocks entrain to whatever photoperiod they're given, whether that matches Earth's rotation or not.

So yes, you can absolutely trick a chicken into laying better eggs by messing with time itself. Just don't ask the hen what day it is—she genuinely has no idea.