Depression shows itself in many different ways. People don’t always realise what’s going on because their problems seem to be physical, not mental. They tell themselves they’re simply under the weather or feeling tired. But if you tick off five or more of the following symptoms, it’s likely you’re depressed:

· being restless and agitated

· waking up early, having difficulty sleeping, or sleeping more

· feeling tired and lacking energy; doing less and less

· using more tobacco, alcohol or other drugs than usual

· not eating properly and losing or putting on weight

· crying a lot

· difficulty remembering things

· physical aches and pains with no physical cause

· feeling low-spirited for much of the time, every day

· being unusually irritable or impatient

· getting no pleasure out of life or what you usually enjoy

· losing interest in your sex life

· finding it hard to concentrate or make decisions

· blaming yourself and feeling unnecessarily guilty about things

· lacking self-confidence and self-esteem

· being preoccupied with negative thoughts

· feeling numb, empty and despairing

· feeling helpless

· distancing yourself from others; not asking for support

· taking a bleak, pessimistic view of the future

· experiencing a sense of unreality

· self-harming

· thinking about suicide.

Source: http://www.mind.org.uk/help/diagnoses_and_conditions/depression