In short
Feeling tired all the time is one of the most common reasons people see a GP. The usual causes are not enough sleep, poor-quality sleep, stress, low mood and low iron. Serious illness is an uncommon cause. If tiredness has lasted more than a few weeks without an obvious reason, a check-up and a few simple blood tests are worthwhile.
On this page
Tired or sleepy?
They are different, and the difference is a useful clue. Sleepy means you could fall asleep if you sat still: nodding off on the couch, in meetings or at traffic lights. That usually points to not enough sleep or a sleep disorder. Tired or fatigued means you lack energy and motivation but wouldn’t necessarily fall asleep. That has a wider range of causes.8
The most common causes
Not enough sleep
Adults need seven or more hours a night on a regular basis.1 Many people get less and adjust to feeling flat. See is 6 hours of sleep enough?
Poor-quality sleep
You can spend eight hours in bed and still wake unrefreshed. Sleep apnoea, insomnia, restless legs, pain, alcohol and night-time hot flushes all break up sleep.
Stress, low mood and anxiety
When researchers pooled studies of people who saw a GP for tiredness, depression and life stresses were the most common findings, and serious physical disease was rare. They concluded that attention should go first to mood and circumstances, not to extensive testing.2
Low iron
Low iron stores can cause tiredness before you become anaemic, particularly in women with heavy periods. In a randomised trial of women with unexplained fatigue and low iron stores but normal haemoglobin, fatigue scores fell by about 48 per cent with iron tablets and 29 per cent with placebo.3 A later meta-analysis found the same pattern: iron reduced the feeling of fatigue in people who were iron deficient but not anaemic.4
Don’t take iron on a guess. Too much is harmful, and low iron needs a cause found.10
Other medical causes
An underactive thyroid, diabetes, anaemia, coeliac disease, infections and their aftermath, pregnancy, perimenopause, and side effects of medicines can all cause tiredness.8,9
Sleep still not right?
Talk it through with an Australian doctor online. No referral needed.
When exhaustion follows activity
If even small amounts of physical or mental effort leave you wiped out for a day or more afterwards, tell your doctor. That pattern, called post-exertional malaise, is the hallmark of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), and it also occurs in long COVID. It matters because the usual advice to push through and exercise more can make these conditions worse. Pacing your activity within your limits is recommended instead.5
Which tests are worth having?
Fewer than you might think. Your doctor will start with questions about your sleep, mood, periods, medicines and alcohol, because that is where most answers are found.5
A small set of blood tests is usually enough: a blood count, iron studies, thyroid function and blood sugar are typical. A Dutch trial in general practice found that ordering a wider panel mainly increased false alarms without finding more real illness.6
What helps
- Protect your sleep. A regular wake time, enough hours, and less caffeine and alcohol in the evening1
- Move more, gradually. It sounds backwards, but across dozens of trials, regular exercise increased energy and reduced fatigue compared with not exercising. The exception is ME/CFS and long COVID, where pacing comes first5,7
- Eat regularly and drink enough water9
- Look at your load. Long hours, caring for others and constant stress are tiring in their own right, and worth naming
- Treat what is found. Low iron, thyroid problems, sleep apnoea and depression all have effective treatments
See also our guides to chronic fatigue syndrome and burnout.
When to see a doctor
See a doctor if you have been tired for more than a few weeks with no clear reason, or if tiredness comes with any of these:
- Unexplained weight loss, fevers or drenching night sweats
- Breathlessness, chest pain or palpitations
- Heavy periods
- Loud snoring, or someone noticing you stop breathing in your sleep
- Feeling very thirsty or passing urine much more often
- Low mood, loss of interest, or thoughts of harming yourself
- Falling asleep while driving
If you are having thoughts of harming yourself, call Lifeline on 13 11 14, or 000 in an emergency.
Next step: talk to a doctor
Answer a few quick questions and you’ll get an email about your eligibility. A consultation doesn’t guarantee any particular treatment.
References
- Watson NF, Badr MS, Belenky G, et al. Recommended Amount of Sleep for a Healthy Adult: A Joint Consensus Statement of the American Academy of Sleep Medicine and Sleep Research Society. Sleep. 2015;38(6):843-4.
- Stadje R, Dornieden K, Baum E, et al. The differential diagnosis of tiredness: a systematic review. BMC Fam Pract. 2016;17(1):147.
- Vaucher P, Druais PL, Waldvogel S, et al. Effect of iron supplementation on fatigue in nonanemic menstruating women with low ferritin: a randomized controlled trial. CMAJ. 2012;184(11):1247-54.
- Houston BL, Hurrie D, Graham J, et al. Efficacy of iron supplementation on fatigue and physical capacity in non-anaemic iron-deficient adults: a systematic review of randomised controlled trials. BMJ Open. 2018;8(4):e019240.
- Latimer KM, Gunther A, Kopec M. Fatigue in Adults: Evaluation and Management. Am Fam Physician. 2023;108(1):58-69.
- Koch H, van Bokhoven MA, ter Riet G, et al. Ordering blood tests for patients with unexplained fatigue in general practice: what does it yield? Results of the VAMPIRE trial. Br J Gen Pract. 2009;59(561):e93-100.
- Puetz TW, O'Connor PJ, Dishman RK. Effects of chronic exercise on feelings of energy and fatigue: a quantitative synthesis. Psychol Bull. 2006;132(6):866-76.
- healthdirect. Fatigue.
- Better Health Channel (Victorian Government). Fatigue.
- healthdirect. Iron deficiency.
This guide is general information, not medical advice. It doesn’t replace a consultation with a doctor who knows your history. In an emergency, call 000.