If you are one of those people who constantly yawn and feel tired all the time, don't blame your age. It's probably your lack of iron, doctors say. 

Women are particularly prone to unexplained exhaustion. Four out of five women in Britain has complained of extreme tiredness. Dr Hilary Jones and nutrition scientist Dr Emma Derbyshire explained that the reason why you could be finding yourself dozing off at work is because of iron deficiency.

A Blood Test Will Tell Your Iron Levels

Iron is important for the oxygen-carrying part of red blood cells - this is why tiredness is usually the first signs of a shortfall, the doctors said. According to Mirror Online, if you don't have enough iron, your red blood cells simply can't carry enough oxygen to your organs and tissue, meaning they don't' work as efficiently.

Doctors have a name for feeling exhausted all the time. It's called TATT, which stands for "Tired All The Time" Syndrome. Doctors say they see a lot of people feeling worn out but they can't figure out what's making them tired from their lifestyle. They then do a blood test to check the iron levels, The Sun reported.

Take Vitamin C To Up Your Iron Absorption

Symptoms of iron deficiency include palpitations, feeling dizzy or fainting, restless legs at night, shortness of breath, cold hands and feet, and headaches, and some are more at risk than others. Menstruation plays a big part in iron loss in women, especially during a heavy period.

One reason why a lot of people have low iron is because a lot are eating 13 percent less red meat than they used to, and red meat contains the most-easy-to-absorb form of iron. But to up your iron intake, you can take Vitamin C since this is capable of improving iron absorption by up to 180 percent.