Why Do Chickens Need Light To Lay Eggs?

Chickens are pretty amazing when you think about it. These extra fluffy birds with the dinosaur-like feet make you breakfast almost every day. 

And while the inner workings of her egg cycle are super interesting, there is one crucial element that makes everything come together-sunlight. 

Why Do Chickens Need Light to Lay Eggs?

Chickens need light to lay eggs because their reproductive cycle depends on it. The process is triggered by the natural light and dark cycle.

This article will explain how chickens lay eggs and why light is crucial to the process. 

How Do Chickens Lay Eggs?

As a chicken owner myself, I can tell you that nothing is more rewarding than walking out to the coop and grabbing those farm-fresh eggs. I always get so proud of my girls that worked so hard! Because egg laying is not easy. 

Let’s take a look at the steps involved.

  • The Yolk is Made
  • The Egg White Forms
  • The Shell Gets Added
  • The Bloom Gets Added

A Yolk is Made

For most breeds of chickens, when they lay eggs. A new yolk is released as soon as a half-hour after that egg is laid. 

Each female chick is born with thousands of yolks, called chicken ova. These are immature yolks that will begin to develop into yolks once the hen reaches 18 weeks old. 

As soon as a new yolk is designated, it will spend the next ten days growing. The yolk will then break out of its protective membrane and plop into the beginning of the oviduct. 

The beginning of the oviduct is also known as the infundibulum. And the release of the yolk takes about thirty minutes.

The Egg White Begins to Form

Once the yolk enters the oviduct, the formation of egg white begins to take place. Next, a protective yolk casing, known as the vitelline membrane, forms, and the yolk then enters the magnum.

Here, thick layers of proteins called albumen begin to form the egg white. This work of art will travel down the oviduct, spinning on its way down.

When the yolk spins, it causes the chalazae to form. The chalazae are the stringy, white pieces in an egg, and their job is to keep the egg yolk from sticking to the shell after it is formed.

It Starts to Look Like an Egg

The forming egg will spend an hour in the isthmus. It is there that the inner and outer membranes of the shell are added. And it is here that that infamous oval shape begins to take place. 

The Shell Gets Formed

The most important part of making an egg happens in the chicken’s shell gland, or uterus. The maturing egg will spend about twenty hours here, where the shell is crafted and the color is added. Remember, not all chicken eggs or white or brown!

The proper diet of a hen comes into play here as this is where nutrients are needed to form a hard shell. Roughly half the calcium from a hen’s diet makes the eggshell. If her diet isn’t sufficient, shells can be soft or brittle.

The Bloom is Added

As the shelled egg travels to the vaginal area of the hen, the bloom is added. The bloom is a protective coating that keeps the egg free of bacteria. A lubricant is also added to the egg so it can safely exit the hen’s vent.

Within a half-hour, this process repeats.

Why is Light So Important for Egg Laying?

The sunlight stimulates the biological process of laying the eggs, and it also drives the production of Vitamin D, which is crucial for egg production. 

When light reaches a chicken’s brain, a process begins. The brain’s photoreceptors capture the light, and it begins to produce amino acids. These amino acids, or neuropeptides, stimulate the production of the hormones needed to complete the egg cycle. 

Will Any Kind of Light Do?

It takes a special kind of light for a special job. For example, the spectrum of light we see with our naked eye covers violets through reds, which are at the higher end of the spectrum. It is this red light that is needed to lay eggs.

The higher the wavelength, the better, as they can pass through the skull and into the hen’s brain, where it stimulates the hypothalamic photoreceptors. The light spectrum will also increase the number of eggs laid.

How Many Hours of Light Are Needed?

A new hen will begin laying her eggs once the daylight is between fourteen and sixteen hours a day. Combined with eight hours of darkness, these sixteen-hour photoperiods regulate the egg-laying cycle in hens.

Most of this light will be natural sunlight from late spring to early fall, depending on where you live. You can add supplemental light to keep egg production up through the darker months of the year.

What About Supplemental Lighting?

It should be said that not all backyard chicken moms and dads favor using supplemental lighting over the winter. I’m not a fan of it myself, as I feel the girls should be given a break, and it also messes with their natural clock. However, with that being said, it is still entirely safe to use supplemental light.

All supplemental lighting should be in the red, high end of the spectrum to stimulate the hen’s reproduction cycle.

What Type of Supplemental Light Should I Use?

Gone are the days of the old light bulbs that sent your electric bill through the roof. Today, different kinds of light bulbs are safe, durable, and earth-friendly. 


The incandescent lightbulb is your old school light bulb. They give off a great deal of light, but they are also more expensive. These can also work on a dimmer switch, making it easy to adjust the intensity.


Fluorescent bulbs are less expensive but more difficult to use in a chicken coop due to the dust. In addition, it’s not as easy to regulate the intensity, especially during the cold winter months.


You almost can’t go wrong with LED lights, as they are the most energy-efficient and are also very reliable in cold weather.

Be Safe About It

Anytime you use anything electrical or flammable around animals, you should use great caution. Ensure all the wires and lights are not within reach of your hens. In addition, you want the lights to be a safe distance from their feathers, their bedding, and other flammable materials. 

Managing the Light and Dark Cycle

Any supplemental light you will use should be slowly introduced to your hens in the early morning hours when they are still sleeping. Then, increase the lighting by about thirty minutes each week until you have reached your ideal goal.

You don’t want any dramatic shifts in light as this can be very stressful for the flock. And remember that they still need eight hours of darkness to maintain the circadian rhythm of your chicken.


Light is essential for chickens to lay eggs. We’ve learned that without light, your hen’s body would not be able to go through the amazing process of producing an egg. And in cases where there is not enough sunlight, adding artificial light can help.

Related Articles