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Are you Using Circadian Rhythms to take your Thyroid Replacement Hormone?

Thyroid Hormones, whether created in the body, or manufactured and found in a bottle, are all about getting 'ENERGY' to where it is needed in each and every individual cell of your body!

The Thyroid Pathways can be complicated and the correct production and conversion of thyroid hormones is affected by many things and many interactions with other endocrine and major organs and their associated hormones.

It is true that often when we find out that we have a thyroid problem, that the measuring of our hormones becomes one of the key things we focus our attention on. However, we often do not think about the variation of levels that those hormones go through each day, or why they are ever changing in response to the different tasks or situations we find ourselves in each day!

For example, if we are doing a lot of energetic and strenuous physical work, our energy demands on the cellular level of our muscles and our bones etc. would be different to a relaxed and lazy day.

Equally, if we are in stress, at a situation or the threat or thought of an upcoming worrying situation, our body will be using a lot of energy through the hormonal pathways, as we convert high levels of adrenaline or cortisone and our body gets ready for the situation or conflict that we are imagining and expecting to happen!

Different types of energy are required for these different body functions - but it is still ENERGY!!

The THYROID is JUST ABOUT PRODUCING ENERGY. It does not get concerned about how it is being used.

So if our thyroid is producing hormones to provide us with usable energy every day - it may just be worth looking at how the day may affect our hormone levels, right?

You might be surprised to know that an under-considered aspect of thyroid hormones is that the levels change during the day.

Yes! Your Thyroid Hormones, especially fT3 and TSH are regulated via Circadian Rhythms!!

Circadian Rhythms

What are these?

The term circadian comes from the route 'circa' (latin meaning "around"); 'diem' (latin meaning 'day).

These 'rhythms' are what we are referring to as the repeated 'completed' cycles that we see in nature that underpin how and when we act in the World. They create patterns of behaviours that define when we need to eat, to sleep, to hunt, to rest etc.

We are also always responding to other rhythms - including ultadian rhythms (being shorter than a 24 hour period: such as a sleep cycle) and infradian rhythms (being longer than a 24 hour period: such as menstrual cycles or seasons).

Times & Seasons for all things

So it seems reasonable, when we think about it, that our energy requirements and levels would change throughout the natural 24 hour cycle.

For many of us (who do not work shifts, or night work), the above image helps us to identify that many different body systems are operating differently at different times of the day - depending upon what is the usual 'pattern' of activity for a normal day.

In the image below, we can see that a lot of our hormonal activities are occurring at night.

They include: TSH (Thyroid Stimulating Hormone) levels increase, Leptin levels increase, HGH (human Growth Hormone) levels increase &

Melatonin, which is the hormone responsible for helping us to sleep.

It is well known that many of our rest and repair functions are happening during sleep time - and it would seem reasonable therefore for us to consider that the increase of the hormones used during sleep time might be related in some way to those rest and repair functions.

Thyroid Hormones & the 24 hour clock

TSH is at its peak levels between 02:00 and 04:00hrs and at its nadir (lowest) levels between 16:00 and 20:00hrs.

Studies have shown that there is a correlation between our TSH levels and our fT3 levels.

There is an increase in fT3 levels that occurs approximately 90 minutes after the increase in TSH levels!

However, there is little evidence of fT4 levels changing. This can be due to the longer half-life of fT4 (of7.6 days) as compared to fT3 (of 3/4 of a day) - meaning that fT4 does not fit into a circadian cycle and therefore making it not measurable as a circadian rhythm).

It can be helpful to understand the peaks and troughs of our thyroid hormone levels over the 24 hour period for reasons we will look at at the end of the article. But suffice to say, that it is important for us to recognise that our hormone levels are always responding to many different things: our physical activity, our stress levels - and the natural circadian rhythms of each day.

As these natural internal circadian rhythms, which directly affect our hormones, are impacted and directed by daylight, (and lack of it) it is sensible to consider that the length of daylight in our days and therefore the seasons may also affect our thyroid hormones!

It is useful to take a moment to look at the impact of light, and its affect on our hormones - especially as this is highly relevant to our modern World and how many of us live! So understanding the impact of light - specifically 'blue light' - on our biological functions, might help us to make different lifestyle choices when it comes to our behaviors...

Getting out of synch

More of us are now aware that 'BLUE LIGHT' is emitted from our electronic toys! And more frequently, people use their hand-held devices to read before bed, to catch up on the news of the day, or socialize through social media platforms.

The time that we used to allow our body to 'power-down' , which traditionally occurred as the natural light diminished is now filled with TV's, electronic lights and the greater brightness of your mobile or computer!

Blue light emitted from these is brighter and is a direct light source which our eyes are directly focused towards. This stops the natural language of 'light' itself (or the diminishing light more specifically) from activating the hormonal pathways that regulate our endocrine system!

That is a BIG problem if you have an endocrine issue (so that includes thyroid issues)!

So - What does all this mean?

One study showed that TSH levels HAVE to change by as much as 72% in order to affect a change on our fT3 levels! If we think about that for a minute - there is as much as a 72% variation in our TSH levels from the lowest point of our TSH production: between 16:00 and 20:00 and our highest time of TSH production: 02:00 and 04:00.

It states that: "There are many variables that determine the biological action of a hormone: rhythmicity, absolute level, affinity for receptor, and receptor occupancy required for maximal intracellular signaling. The observation that FT3 levels are dependent on an approximate 72% change in TSH levels from nadir to peak confirms that at these serum concentrations,the variation in level of TSH has a biological action"

  • The implication of knowing that your TSH levels can change that much, might be useful when you arrange what time to go and get your blood levels checked?

  • The correlated circadian rhythms of TSH & fT3 may be helpful to consider when deciding when is the best time of day for you to take your Hormone replacement tablets?

  • Thinking about Circadian rhythms more consciously might help you to make lifestyle choices that keep you more in synch with those natural rhythms! Let your Body GET READY FOR A GOOD NIGHTS SLEEP! Naturally!!

T3 Hormone Replacements:

Knowing that TSH levels increase during sleep time, may impact when you chose to take your hormone supplements: For example, fT3 would naturally be increasing through the early hours of the morning, and decreasing towards the end of the day. So a hormone replacement that has T3 in it might be better taken in the early morning. Waking at 6 and taking your tablets early would help to keep your body in line with the natural cycles, whereas taking a T3 tablet at night might potentially affect the natural balance that occurs between the TSH hormone and fT3. What I mean by that is that there is a possibility that by taking T3 in the evening it might inadvertantly be interfering with the natural TSH production (given that TSH production is a precursor to our normal T3 production cycles). This is only my supposition from the data, and not one I have found studies on.

T4 Hormone Replacements:

If you are taking T4 hormone replacement, the infradian cycle of T4 and its slow half-life, means that it may be less likely to affect TSH levels on a daily basis.

As in all things, these are thoughts and guidelines around when you might consider having your blood test taken and what time you might chose to take your tablets each day. They are not set in stone, and as said, hormones are always changing - also based on physical requirements and emotional and other stresses.

So LISTEN TO YOUR OWN BODY - and make the changes that suit you best!


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