Having untreated depression can put your life on hold for months, if not years.

Read on to discover the 10 of the main symptoms of depression.  If you experience one or more of these symptoms, talk to your doctor.

1. Lack of Motivation

Depression often causes people to lose interest in things they used to enjoy. If an outgoing person begins to consistently turn down invitations from friends to go on trips or to have fun together, it could be that he/she is struggling with depression. Sometimes the person starts to neglect hygiene and their personal appearance. They might also fail to keep their responsibilities towards other people. What were once normal, social interactions may now cease to appeal to them.

2. Hard to Make Decisions

Research shows the average person makes around four or five decisions per hour. The vast majority of these decisions require little forethought, but a person struggling with depression can find even the smallest decisions hard to make. Everyday life can become difficult when normal thought processes are interrupted in this way. Alongside the indecisiveness, people suffering from depression may also find it hard to concentrate, and they frequently become forgetful.

3. Low Self-Esteem

It is easy to understand how feelings of low-self-esteem develop or worsen when dealing with depression. Unable to effectively carry out their activities, people with depression can alienate family and friends. People in this state often fail to recognize they have an illness. Often, they naturally come to blame themselves for their social problems and personal failings, which can send their self-esteem plunging.

4. Guilt

Anyone with depression may develop irrational or disproportionate feelings of guilt. This may come as a result of not meeting their responsibilities, or when they recognize how easily they become irritated by the actions or words of others. The emotional reaction typical of depression is out of proportion to how a healthy person would generally feel under the same circumstances. Worse, a sense of being unable to correct the spiral of guilt and regret can exacerbate these feelings, creating a runaway emotional tailspin. People going through this often develop the low-esteem that is another common sign of depression.

5. Irritability

People with depression sometimes become intolerant of the behavior of others around them. The difficulties they face in handling regular challenges and the behavior of other people can make them feel anxious and edgy. They may easily "flare up" in an outburst more severe than they intended. People struggling with depression are also more inclined to interpret innocent words or actions negatively. The difficulty this creates in dealing with others invites criticism, but they may be unable to deal with this calmly.

6. Anxiety

People going through depression frequently become concerned about what's happening to them. Mysterious physical pains, fatigue, loss of appetite, problems concentrating, and other issues linked to this illness give them the impression they might be suffering from serious physical ailments. The anxiety this causes increases if the symptoms don't go away on their own. To get a medical diagnosis of depression might come as a relief in this situation, even if it doesn't make dealing with these symptoms much easier

7. Suicidal Thoughts

People with depression often develop a pessimistic view of their life. Some of them start to think about death, though only a few seem willing to talk about it. Those who do might speak of their hope that it will soon be all over with for them, or that their pain might end soon. This kind of talk frightens those close to the person. Much of the time, this kind of speech only reflects their low mood, and most genuinely have no intention of doing anything rash. There is, however, a significant link between depression and risk of suicide. Every threat of suicide has to be taken seriously, and doctors and mental health professionals need to assess the dangers of the person harming themselves or others on a case-by-case basis.

8. Changes to Menstrual Cycle

Researchers estimate that more than one-fifth of women suffer depression at some time. This condition affects the hormone balance in the body, which can make women with depression more likely to experience irregular menstrual cycles. Periods might come much later than usual or be missed, and the chances of getting pregnant generally fall. Many other health conditions can also affect menstrual cycle regularity, but if a woman with irregular menstruation has four or five other symptoms of depression, there's a chance her fertility issues are linked.

9. Disturbed Sleep

Disturbed sleep is one of the most common symptoms of depression. This illness disturbs sleep in various ways. Some people with depression find it hard to get to sleep, while others wake up in the early hours of the morning and cannot get back to sleep. Others sleep in and might not get out of bed until mid-morning or early afternoon. Sleep deprivation adds to people's fatigue and significantly reduces their ability to carry out daily activities.

10. Pains

Depression can cause a variety of mysterious pains. This can include headaches, aches in different parts of the body and even chest pains. Because these symptoms can be caused by serious physical ailments, they should never be taken lightly. Chest pain, in particular, should always be checked out by a doctor for a diagnosis. Depression-linked pains can cut both ways: sometimes the pains are a symptom of depression, and sometimes people who suffer from pain-inducing physical ailments become depressed as a result. In any case, it pays to err on the side of caution and investigate the source of the pain.