Brain cancer is caused by cells multiplying in an abnormal way, according to the NHS.
Symptoms of the condition are caused as the tumour takes up space inside the skull.
The signs can develop over a period of time, and patients may not show any symptoms to begin with.
But, you should see a GP if you’re feeling persistently drowsy.Related articles
Some symptoms of a brain tumour are very general and lots of other medical conditions can cause them
Cancer Research UK
“Some symptoms of a brain tumour are very general and lots of other medical conditions can cause them,” said Cancer Research UK.
“It's unlikely to be a brain tumour, but always get your symptoms checked out.
“You might find you feel drowsy or you are sleeping more. You might be falling asleep during the day.”
The NHS added: “See your GP if you have the above symptoms, particularly if you have