What is cortisol?

Cortisol on your report

Cortisol is usually tested in blood, often in the morning and again around 4 pm, or in urine or saliva.

Because it changes through the day:

• the time of the sample matters
• labs print their own ranges for different times

What cortisol tells your doctor

Cortisol follows a daily rhythm: it is highest in the morning and much lower by late afternoon.

Stress and exercise push it up for a while, which is normal. Problems come when it stays too high or too low for a long time.

• Too much, as in a condition called Cushing's syndrome, can cause weight gain, a rounder face, easy bruising and muscle weakness.
• Too little can bring tiredness, weight loss and weakness.

These can also raise it:

• anxiety and depression
• heavy drinking
• poorly controlled diabetes
• obesity

What moves your cortisol

Everyday habits shape how your stress system runs. These all help:

• a fixed sleep and wake time
• regular meals instead of long gaps followed by big ones
• movement you enjoy, like brisk walking or yoga

Simple slow breathing or a short quiet break in a busy day can ease stress.

Long-term steroid medicines are the most common cause of abnormal cortisol, so never stop one suddenly on your own; talk to your doctor first.