Sunlight, Energy and Sleep Part 1: Circadian Rhythm

I’m going to start with a bold statement:

Wearing sunglasses in the morning is one of the WORST things you can do for the health of your energy and sleep.

Your circadian rhythm and all the things associated to it are the cornerstones of health. We have a nuclear fusion reactor in the sky that emits a wide spectrum of light energy that we as humans have developed over millennia to use to our advantage. Almost all of the important processes related to health and wellbeing can be tied back to sunlight. Whether it is the formation of vitamin D that I’m sure you will be aware of, all the way through to the benefits to your immune system, energy and sleep.

Part one of this series is going to cover how light signals from the sun positively affect your circadian rhythm and health; and how blocking them by not going outside or wearing sunglasses can cause a cascade of negative effects to your energy and sleep.

What is your circadian rhythm?

Your circadian rhythm is an internal body clock set around a 24 hour(ash) period of time. It is what controls your sleep/wake cycle. How awake/alert you feel and the processes related to sleep are directly affected by your circadian.

If it takes two to three hours and as many coffees in the morning before you start to feel yourself, your light habits both in the morning and at night can affect this. If you have trouble getting off to sleep, it could be because your habits around your evening time are preventing your hypothalamus from helping to kickstart the internal processes related to sleep.

The down stream affects of a balanced or unbalanced circadian rhythm is profound.

Here are a the major systems your circadian affects:

• Metabolism

• Normal, daily fluctuations of internal temperature

• Hormonal balance and secretion

• Digestion

• Cell repair

• Metabolic balance and flexibility

• Immune system

What controls your circadian and what choices can you make to help improve your internal clock?

The first and most important factor that affects your circadian is light. Sunlight to be exact. Not sunlight through windows as unfortunately, glass filters out all of the useful rays required to make a positive effect on your circadian. Bright indoor lights are better than no lights at all, but they are limited in their bandwidth of light waves and even the brightest ones don’t really match that of the sunlight. In short, they don’t cut it if you want to make a real impact.

As you can see from the following image, we can only see a certain amount of the light frequencies emitted by the sun. Indoor lights (unless programmed to) do not emit the upper ranges of IR light or UV light, both of which have important uses.

Morning light has a particular breadth of frequencies of light that clocks you in so to speak for the start of your 24 hour cycle. Morning light has different amounts of red light, blue light etc than what midday light has which is what makes morning light critical for maintaining or correcting circadian rhythm.

Light waves travel from cells in your eyes to a portion of your brain called the Suprachiasmatic Nucleus or SCN for short. The SCN sits within the Hypothalamus region of the brain. Its important to know this because the hypothalamus is a pretty big deal when it comes to the brain.

Think of the hypothalamus as the control centre for homeostasis or balance in the body. It’s role is to keep us in a stable state and it controls the inner workings (signalling of hormonal release etc) going. If things are out of balance, our health and wellbeing decline.

The SCN adjusts your circadian based on light inputs. For example, dimmer, more red/orange wavelengths of light emitted in the evening cause the SCN to tell your pineal gland in your brain to start producing melatonin. Melatonin is an important hormone that when secreted helps to synchronise cells in your body to your circadian. It is also a super potent antioxidant! Exposure to bright light in the evening delays the processes related to sleep (such as melatonin release), thus delaying your ability to get to sleep. This is why it is super important to keep your evening light environment as dim as possible.

Morning sunlight is often brighter, more crisp or white in appearance. It is this nice, bright morning light that signals to you brain to WAKE UP. Wearing sunglasses blocks these all important wavelengths reaching your eyes and in extension, the SCN in your brain.

If you struggle with energy in the morning oo even getting off to sleep at night the key is to expose yourself to natural morning light and dimmer, more orange/red shades of light in the evening. Turn those extra lights off!

How does a unbalanced circadian affect energy?

Your circadian times the secretion of enzymes and proteins in your digestive system in line with your normal eating patterns Your endocrine system also releases hormones that are critical for energy expenditure in accordance with your 24 hour clock. This affects things like the availability of nutrients to you and also your blood glucose both at rest and during activity. Both hugely critical factors that affect how you feel each day.

A dysregulated circadian will also impact the hormones leptin and grhelin which are control feelings of hunger and fullness. Leptin is what signals to the brain that you are full and like the other hormones impacted by circadian biology increases and decreases throughout our 24 cycle. People who have a disrupted circadian have shown to have lower levels of circulating leptin in contrast to those with a balanced sleep/wake cycle. Less leptin impacts your metabolism whilst increasing hunger levels. Not an ideal combination as this can lead to eating more, gaining excess body fat, higher increases in resting blood sugar and possible negative effects on the menstrual cycle in women.

These are just snapshots of the greater picture but give you a decent idea of the impact that the circadian rhythm has on your health and wellbeing.

Making lots of small changes can have a profound effect on your biological 24 hour clock and nearly all of them are completely free. This starts by not wearing your sunglasses in the morning and getting outside for some morning sunlight.

Further reading:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6751071/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3603689/