Depression is a mood which can affect us all, and we would not be human if we never felt it. It is normal to feel depressed after illness, even flu, or bereavement, or if something sad happens. Sometimes it is a sign of stress. The feeling can last a few weeks, or months, depending on the cause, and gets better on its own.

Depression is also a very serious illness which affects many people at some time in their lives. It shows in a variety of ways, and you do not have to feel sad or down to be ill with depression. Common signs are:

• tiredness or lethergy
• lack of interest and low motivation
• poor sleep, particularly waking early
• loss of appetite or enjoyment of food
• feeling generally unwell
• bouts of uncontrollable weeping or tearfulness
• feelings of meaninglessness or wishing to take your own life

Like other illnesses it is curable, with the right treatment.
You may like the idea of medication to calm things down and help you sleep, and cope better generally. Therapy can also be helpful in finding ways for you to manage better. As a therapist, I like to use both, as the medication helps my side of the work.
Much depression will even get better on its own given long enough, but if you decide to take that route, remember that it is the most common cause of suicide. People die of it, so do seek help.