What should you know about daytime fatigue?

Fatigue is more than feeling sleepy after a busy day: it can mean low energy, reduced concentration, or difficulty completing usual tasks. Contributors include disrupted sleep, dehydration, alcohol use, burnout, recent infection, anaemia, coeliac disease, chronic kidney disease, or chronic fatigue syndrome. COVID-19 can also present with fatigue. The pattern matters: note whether it began suddenly, follows poor sleep, appears after exertion, or comes with weight change, breathlessness, pain, mood changes, or memory problems.

Keep a brief diary of sleep, naps, medicines, food and drink, activity, and the times fatigue is strongest. Keep regular sleep and wake times, get daylight and gentle movement, drink regularly, and avoid using alcohol as a sleep aid. Do not drive or operate machinery when drowsiness makes you unsafe. A clinician may review medicines and ask about sleep, mood, diet, bleeding, and other symptoms before deciding whether examination or blood tests are needed.

Seek urgent help for sudden weakness, trouble speaking, severe breathlessness, chest pain, fainting, new confusion, or thoughts of self-harm. Arrange a medical appointment when fatigue persists, interferes with work or daily care, follows a significant illness, or comes with unexplained bleeding, fever, swollen glands, or worsening mood. Prompt review is also sensible when daytime sleepiness causes near-misses while driving.

Could a medicine, sleep problem, or medical condition explain my fatigue? Which symptoms should I track? Would an examination or blood test help identify a cause?