If you find yourself nodding off during the day or constantly yawning through meetings, your body could be under siege from hidden energy sappers.
But instead of reaching for another coffee, it's important to find the root cause of tiredness - which could be a symptom of an undiagnosed health condition.
Here, I reveal common causes of fatigue - and the best way to get your energy level back on track...
Instead of reaching for another coffee, it's important to find the root cause of tiredness - which could be a symptom of an undiagnosed health condition, says nutritionist Dr Marilyn Glenville
Around four million women in the UK suffer from anaemia, caused by lack of iron.
The symptoms include tiredness, dizziness and a racing heart. Your body needs iron to produce red blood cells, which carry oxygen around your system.
Without it, you’ll feel lethargic, no matter how much sleep you get.
It is better not to take iron unless you know you are anaemic. If you do take it, it's important to get re-tested to check your levels are back to normal.
Energy solution: If you suffer from tiredness and heavy periods, then ask your doctor for a blood test for VWD (Von Willebrand’s disease).
This affects around 300,000 women in the UK and is caused by blood not able to clot properly.
Your doctor also needs to test your iron levels. To reduce the risk of anaemia, make sure eat a balanced diet with plenty of green vegetables.
Not how, but when you work out could be draining your energy.
You should not exercise intensely just before bed, as this will make your adrenaline, heart and respiratory rates pump and you won’t be able to sleep.
Also if your exercise routine is too intense, long or vigorous for your current level of fitness, instead of energising it will be draining you.
Energy solution: Do energy forming exercises such as running or aerobics in the morning and focus on milder activities later in the evening.
Try a walk at the end of the day or a yoga session to calm your mind and stretch your muscles.
If your daily exercise routine is exhausting, then adjust it. The aim of exercise is to boost your energy not drain it.
But don’t go the other way though and cut out exercise altogether! No exercise will trap you in an vicous cycle of tiredness.
Around 30 minutes of light exercise a day can help boost energy levels significantly.
THE IRON DEFICIENCY EPIDEMIC
If fatigue has become a fact of life and your usual workout routine is becoming seriously hard work, you could be one of millions of people who are not getting enough iron.
Iron is essential for energy because it's a building block for the red blood cells that transport oxygen around the body — which explains why constant tiredness is a tell-tale sign that you aren't getting enough.
Other tell-tale clues are headaches, dizziness, tinnitus — hearing sounds which seem to come from within your body, hair loss, cold hands or feet, difficulty swallowing, feeling itchy, disturbed sleep, lack of appetite, abdominal pain, having a sore or unusually smooth tongue, or brittle or spoon-shaped nails.
Red meat is one of the richest and most useful sources of iron.
Tiredness is one of the most common side effects of depression - along with lack of motivation
As well as loss of libido, weight gain and lack of motivation, one of the most common side effects of depression is tiredness.
Energy solution: As well as eating healthily and getting the mood-boosting effects of regular exercise - preferably in the fresh air - you may want to try some cognitive behavioural therapy (CBT).
This is recognised as effective in helping to change the patterns of your mind so that you can control stress and depression.
The herb St John’s wort is also effective for mild to moderate depression.
UNDIAGNOSED DIABETES OR BLOOD SUGAR PROBLEMS
Figures show there are more than 500,000 people in the UK with undiagnosed diabetes.
The condition is partly to do with high sugar diets, obesity and sedentary lifestyles.
It occurs when the amount of glucose (sugar) in your blood is too high and your body is unable to convert it into energy, as there is not enough insulin or the insulin produced isn’t working properly.
The body then breaks down its stores of fat and protein to try to release more glucose and the problem gets worse.
This is why people with untreated diabetes feel tired and lose weight. Other symptoms include urinating often and extreme thirst.
Cravings for starchy, sweet or fatty foods before your period can mean you have a blood sugar imbalance
Energy solution: Ask your doctor for a blood test. If the test is negative for diabetes then your tiredness might be caused by your blood sugar levels.
Cravings for starchy, sweet or fatty foods before your period can mean you have a blood sugar imbalance.
To keep your blood sugar levels steady avoid sugar and refined processed foods as well as juices, cigarettes and caffeine.
Eat every three hours and load up on low glycaemic foods such as seafood, eggs, hummus, green vegetables and fruits such as pears, grapes and apples.
Replace pasta with basmati rice and have porridge for breakfast instead of packaged cereals.
Dehydration occurs when you lose more fluid than you take in. Your body doesn't have enough water and other fluids to carry out its normal functions.
Mild dehydration can cause symptoms such as weakness, dizziness and fatigue.
Inadequate intake of water during hot weather or exercise also may deplete your body's water stores.
More obviously, other ommon causes of dehydration include intense bouts of diarrhoea, vomiting, fever or excessive sweating.
Energy solution: You can usually reverse mild to moderate dehydration by increasing your intake of fluids, but severe cases need immediate medical treatment.
The safest approach is not to become dehydrated in the first place.
Aim for 6 to eight glasses of water or herb teas a day and don’t wait until you get thirsty to drink.
You can do that by monitoring your fluid loss during hot weather, illness or exercise, and drinking enough liquids to replace what you lose.
Reduce your alcohol, tea and coffee intake as these are dehydrating.
VITAMIN B12 DEFICIENCY
If you feel tired and are eating a healthy diet, you may be deficient in vitamin B12, which helps to carry oxygen around the body and it is a must for energy.
Energy solution: You may want to ask your doctor for a blood test to check your levels of B12. Injections can then be administered by your doctor if needed.
Use your bed for sleeping and sex only, so you associate it with rest and pleasure only, says Dr Glenville
Almost 40 per cent of the population suffers from some form on insomnia.
A disrupted night’s sleep affects you physically and mentally. In the long run, you end up with a massive sleep debt that you body can’t repay no matter how much of it you get.
Energy solution: To increase your chances of a good night’s sleep make sure your bedroom is a calm and relaxing place and your mattress is comfortable.
Use your bed for sleeping and sex only, so you associate it with rest and pleasure only.
Block out noise and light, as light will impair the production of the sleep hormone, melatonin.
Try to sleep in a well ventilated but not cold room (around 13 -18° C, 55-65° F), as body temperature falls at night to promote feelings of sleepiness.
Your thyroid works by producing the hormone called thyroxine, which controls metabolism and regulates energy levels.
If your thyroid produces too little of it you feel tired. You might gain weight, your skin and hair will feel dry and you may also feel depressed.
Energy solution: Ask your doctor for a thyroid test. If you have an under active thyroid he or she will prescribe medication to boost your hormone levels. You should also eat a diet high in fruit, vegetables, fish and seaweed and avoid alcohol and cigarettes.
Food intolerances trigger an immune response which uses up a huge amount of energy, Dr Glenville says. 'The most common food culprits are wheat, dairy and sugar. So if you eat a cheese sandwich on whole wheat bread, you may be using up energy by simply digesting rather than converting your lunch into energy'
One in 10 people in the UK has a food intolerance which can cause lethargy and irritability.
Food intolerances trigger an immune response which uses up a huge amount of energy.
The most common food culprits are wheat, dairy and sugar.
So if your lunch was a cheese sandwich on whole wheat bread with a bar of chocolate your body may be using up energy by simply digesting rather than converting your lunch into energy.
Energy solution: If you suspect that you have a food intolerance keep a food diary for a few weeks and see if there is a connection between your tiredness and a specific food.
Try eliminating that food and see if it makes a difference. Alternatively you can have a blood test to check for food allergies.
Dr Marilyn Glenville is author of The Natural Health Handbook for Women.