As health problems go, it's one of the most common out there, and one of the hardest to pin down. Feeling tired all the time - which often goes by the acronym TATT - might simply indicate that you're not getting enough shut-eye. Depending on your particular circumstances, this problem should be easy enough to fix. But if you're feeling truly exhausted, and can't pin it on any obvious cause, the situation might require a bit more attention.
As Professor Helen Stokes-Lampard, chair of the Royal College of GPs, explains: "Feeling tired after a long and busy day can affect all of us from time to time and is a natural response to pushing ourselves hard. This can often be rectified by getting a good night's sleep, eating well, and keeping hydrated. But it's important to be aware of the difference between normal tiredness, which is very common, and abnormal fatigue."
If you have the kind of tiredness that doesn’t go away, even after a good night's sleep, it may be worth investigating the situation more closely. This is especially the case if you're experiencing other symptoms, have been tired for more than four weeks, or think you might have an underlying condition.
"If a patient has been experiencing a prolonged lack of energy for no apparent reason, they should seek advice from a healthcare professional," says Professor Stokes-Lampard.
Patient's clinical director Dr Sarah Jarvis agrees. "Tiredness isn't a disease, it's a symptom - and one we've all suffered at some point. There may be an obvious cause, like jet lag or disturbed nights. But if your tiredness doesn't settle or is affecting your life, it's worth getting it checked," she says.
Excessive tiredness is something that strikes many of us every once in a while. According to the Royal College of Psychiatrists, one in five people feel unusually tired at any given time, and one in ten have prolonged fatigue.
Often, the causes are psychological, which is not to say the exhaustion is somehow 'all in your head'. Rather, if you're going through a particularly stressful period, be that a house move or a hectic time at work, you'll often feel drained as a result.
For one thing, you may not be sleeping as well as normal. For another, if you're under stress, your body goes into 'fight or flight' mode, sparking up a series of hormonal and physiological changes. If this stress response is activated frequently, you may end up feeling fatigued.
Some alternative medicine practitioners attribute this kind of tiredness to 'adrenal fatigue' - ie an inability to produce the amount of adrenaline you need. This is not a proven medical condition, however, and you should steer clear of remedies that promise to cure it.
Although some life stress is unavoidable, it's particularly important to seek help if you think you may be suffering with anxiety, depression or another mental health condition like PTSD. These conditions are often accompanied with fatigue, as well as sleep problems like insomnia.
"Of course there is no simple blood test or scan to diagnose depression. However, if you've also been feeling down, depressed or hopeless, or haven't been enjoying life as much as you were, depression could lie at the root of your tiredness," points out Jarvis.
Some people feel caught in a vicious circle, in which their depression exacerbates their insomnia and their insomnia exacerbates their depression. Although there can be a temptation to self-medicate with alcohol, it's best to steer clear as this can make both problems worse.
There can be physical causes for 'TATT' too, although they're less common than the psychological ones.
"A prolonged state of lethargy can sometimes be a symptom of a serious underlying condition, such as type 2 diabetes, coeliac disease or anaemia,” says Stokes-Lampard. "Patients are rarely fatigued in isolation, and will often experience other symptoms. For example, with respect to coeliac disease, patients might also feel bloated or have diarrhoea, and experience weight loss."
"For type 2 diabetes, along with tiredness, you may feel more thirsty, need to pass urine more often or get more minor infections like boils or recurrent thrush," adds Jarvis.
Other issues that can cause fatigue are thyroid problems like hypothyroidism, infections such as glandular fever, or sleep disorders like sleep apnoea. If your doctor suspects any of these causes, he or she will run a physical test.
Less commonly, you might be suffering with chronic fatigue syndrome, also known as ME, which is characterised by extreme tiredness along with symptoms such as foggy-headedness and muscle pain. Unfortunately, there is no specific test to confirm the diagnosis of ME. You'll be diagnosed only when other conditions are ruled out.
ME can range in severity from relatively mild to extremely disabling. While most people do eventually recover, there is currently no cure, and symptoms may take a relapsing-remitting course. A related condition, fibromyalgia, can also cause chronic fatigue.
Beyond these causes, tiredness can be a side effect of certain medications, and it is to be expected if you're currently pregnant, or have gone through surgery or chemotherapy. You're also more likely to suffer tiredness if you're very overweight (as your body has to work harder day-to-day) or underweight (as your muscles might not be very strong).
Avoid the sugar crash
If you don't have an underlying condition that requires treatment, making a few lifestyle changes might be enough. To begin with, it's worth re-evaluating your diet. Steer clear of refined carbohydrates, as these provide a short-lived energy spike, followed by a crash that leaves you craving your next sugar hit.
As Patient's nutritionist Rose Constantine Smith explains, it's important that each meal provides a good balance of nutrients.
"Try to include a portion of lean protein, vegetables and a source of complex carbohydrates such as whole grains, potatoes with skins on or pulses," she says. "These are broken down slowly by the body, thus providing a steady supply of energy to keep you going until your next meal. If, however, you are in need of a pick-me-up between meals, opt for natural sources of quick-release energy alongside a harder-to-digest food that will slow the release of sugar into the bloodstream."
A few examples might be dried fruit with nuts; yoghurt with chopped fresh fruit; or a slice of wholegrain toast with a thin layer of peanut butter.
"Coffee with a splash of milk may also provide a much needed pick-me-up if you are feeling particularly tired, and drinking up to three cups of coffee a day is said to be beneficial. Try to avoid having any in the afternoon though, as this may disrupt your sleep!" adds Rose.
Exercise and sleep
As well as tweaking your diet, it's also important to make sure you're exercising enough. This may be the last thing you feel like doing when you're exhausted, but the benefits speak for themselves. Quite aside from the endorphin hit, regular exercise improves sleep quality and gives you more stamina to get through the day.
A word of warning though - more is not always better. So-called 'overtraining syndrome' is real, and athletes need a lot of rest in order to recover properly. Overtraining typically leads to performance plateaus, a higher risk of injury, and - most saliently - fatigue. If that's you, make sure to scale back on your workouts, or take some time off. (And avoid exercising just before bed, as that much sought-after energy boost can leave you unable to sleep!)
One final tip is to look at your sleep itself. How is your sleep quality? Is it being compromised by, for example, afternoon energy drinks, too much screen time before bedtime, excessive alcohol consumption, or naps at odd times? Being a bit stricter about your 'sleep hygiene' can make all the difference when it comes to increasing your energy levels.
Although feeling tired all the time is very common, it isn't exactly 'normal', and it shouldn't be something you have to live with. Make sure to book an appointment with your GP if you've ruled out all the obvious factors and are concerned.