Why am I so tired?!

Everyone's saying it at the moment. Everyone's feeling it. Why?
Hibernation is often the next word out of our mouths – we so envy the squirrels and badgers as they curl up in the warm, and we moan at our bosses for not letting us stay under the duvet each morning.
As autumn and winter set in we seem to be torn over which is the more natural response. Shall we give in to our body's desire for more rest? Or seek more of the natural substances which we believe are good for us (sunshine, vitamin pills, fresh fruit and vegetables) so our bodies can keep active as we aim for a healthy life?
A big factor at this time of year is the number of apparent viruses and infections. We refer to these as bugs 'going round' and comment that we have 'caught' something.
We say we can't 'shake off this chest infection', or we have 'passed our cough on' to another member of the family.
There is no doubt that microbes are very efficient at getting from one human host to another through coughing, sneezing or hands. Yet microbiologists are now beginning to understand that bacteria and viruses can sometimes hang around in all sorts of places in our body without the immune system showing signs of responding at all.
Admittedly a few factors in infectious transmission involve the weather – low temperatures and a low total moisture content of the air create ideal conditions for flu viruses to attach themselves to the mucus-producing surfaces of the body (often the nasal passages).

Research is beginning to show that our immune systems are not always under sudden threat of overwhelming attack when our bodies respond. Our immune systems may instead have 'woken up' to a danger that is already present.
But why might our immune systems go to sleep until then? Surely they are on guard all the time? (See my first blog post for one suggested reason).
A simplified summary of our complex immune response splits it in to two main parts: the innate immune system, which is not yet well understood but involves receptors mounting a standard defence; and the adaptive immune system, where the different types of white blood cells recognise invading pathogens, attack and destroy them.
A healthy immune response in a human body will, once it is fully aware of the danger, rush to remove it. The results of this process can be high temperature, production of mucus, fatigue, inflammation, vomiting, coughing or skin outbreaks – anything to help the body kill off or expel the bacteria.
Does that seem strange to associate these awful symptoms with being 'healthy' internally? Our bodies do so much without us knowing anything about it and scientists are beginning to note that these apparently undesirable symptoms can be helpful, natural responses that keep us healthy.

So, what about times when we only feel tired?
Sleep is an amazingly mysterious thing that is still the focus of much research. But there is already evidence that sufficient sleep contributes to our immunity, and that infection can cause disruption of normal sleep patterns.
Even though nothing else is apparent, I would suggest that tiredness means the body is hard at work doing something that comes naturally. We can't all be subject to close medical scrutiny to find out what is going on inside us at that moment when we collapse on the sofa.

Our first urge when we are fatigued or our bodies seem 'under the weather' is to take away the symptoms and pain. But a lot of commonly used medicines like anti-inflammatories, anti-depressants and prescription steroids actually reduce the functioning of the immune system.
Don't let your immune system go to sleep. Maybe you should give your whole body an early night.
But your boss won't be pleased if you just pull the duvet back over your head each morning.