What is the Circadian Rhythm and what does it have to do with grooming?

The Circadian Rhythm is a body’s internal clock. It is set to 24 hours and regulates bodily functions over that 24–hour period. It is responsive to light and dark cycles. Longer darker periods of time disrupt the Circadian Rhythm resulting in altered sleep patterns. This lack of interrupted sleep may result in a feeling of lethargy. In addition, the amount of daylight versus nighttime affects two hormones: melatonin and serotonin.

Melatonin: The brain produces melatonin when it is dark outside and then halts production in sunlight. Melatonin is what makes you sleepy at night. During the shorter winter days, there is an overproduction of melatonin compounding the already disrupted Circadian Rhythm.

Serotonin: The reduced amount of sunlight also inhibits production of serotonin, also known as the happy hormone. Serotonin is the neurotransmitter responsible for moods. Lower levels of serotonin will adversely affect appetite (more), sleep (less), and memory (did I really eat that whole bag of Stella Doro cookies?)


An altered Circadian Rhythm may make you a tired, hungry, and grouchy groomer.

As the main disruption of this cycle occurs in winter, it is usually referred to as Seasonal Affective Disorder (SAD). However, we can inadvertently make the situation worse by our choice of shop lighting that creates a yearlong SAD. Additional effects of this disruption on a Circadian Rhythm may include migraines, eyestrain, problems sleeping, depression, unhealthy immune and endocrine systems, stress, anxiety, and obesity.


But, did you know that an altered Circadian Rhythm might affect the pets in our care as well?

A 2013 article in Psychology Today by Stanley Coren Ph.D., F.R.S.C. states exactly that premise, and for the very same reasons that SAD affects us. The Circadian Rhythms, along with their production of melatonin and serotonin is thrown off. Seasonal Affective Disorder is estimated to affect 25% of dogs and 33% of cats. Those pets affected may be poorly behaved due to their own crankiness.

While you may not be able to control Mother Nature, you can make lighting changes to a shop to compensate.

The case for letting natural sunlight into your shop comes from the April/June 2012 issue of Dermato-Endocrinology. The study reports that natural sunlight increases production of Vitamin D and the happy hormones such as serotonin and oxytocin, as well as provides numerous other health benefits. Another plus to sunlight is that it is a free resource.

The flip side to allowing sunlight to pass through glass is that it heats the air. In the winter, that may be all right, but in warmer weather, it can be deadly! An air conditioner large enough for your shop is necessary to prevent heatstroke for the groomers as well as the pets in your care. In addition, installing sun glare films on windows may significantly reduce the amount of harmful UV rays and diminish glare, while allowing the natural sunlight to fill your establishment.

There are five choices when it comes to bulb type:

Natural or full spectrum: This light spans the full visual spectrum, similar to that of the sun. You still get the benefits of sunlight without heating up your space or adding UV rays and sun glare. They are available in a wide variety of bulb shapes including most fluorescent fixtures.

Incandescent lights: It is close to full spectrum, but not quite. Neither full spectrum nor incandescent bulbs are energy efficient.

Fluorescent lighting: They have a very limited visual spectrum. They contain mercury, which is hard to recycle and dispose of. Mercury is toxic to just about every organ and system in the body. Most curbside garbage pickup, whether private or municipal, may not accept used fluorescent bulbs. Some municipalities have a specific day to dispose of them. Home Depot and Lowes will take your unbroken bulbs. Fluorescent light also flickers. This flickering may cause migraines, eyestrain, headaches, and interferes with your Circadian Rhythm. The problem with fluorescent lighting is that these bulbs can affect a yearlong “seasonal affective disorder” scenario. It is not the same as daylight, which throws off your melatonin and serotonin production.

LED or light emitting diodes: Red LEDs are made from aluminum gallium arsenide. There is no real research on any health effects on people. However, there are studies that link red LEDS to chronic and acute toxicity of the kidney, lung, and reproductive organs in animals. Blue LEDs may damage the retina of people who are already prone to eye problems. White LEDs are not known to cause any health concerns.

Halogen lights: They emit ultraviolet radiation similar to fluorescent and should be covered with a fixture at all times.

 By replacing the fluorescent and halogen bulbs with either incandescent, white LED, or full spectrum lighting may help reduce the effects of a disrupted Circadian Rhythm resulting in happier, healthier groomers, as well as the pets we groom. ✂