What image comes to mind if I ask you to think of someone who is depressed? Typically we picture someone who’s sad all the time, stays in bed for much of the day, and has no energy. The individual knows he or she depressed, and it’s obvious to others.

While this description may apply to many people’s experiences of depression, it can also obscure the tremendous variability in how the condition manifests itself. In reality, we can be depressed and not even know it. And while the people around us may sense that we’re not at our best, they may not suspect depression, either.

How is it possible to not know when depression is present—a condition often cited as the number one cause of disability worldwide? Several factors can play a role:

  1. Depression onset tends to be gradual. The individual symptoms of depression can develop so slowly that we don’t notice it’s happening, like hair growing—there may be no noticeable change day to day or even week to week. But give either enough time and the differences will be obvious. Since we’re with ourselves all the time, we may not notice subtle changes in our mood, energy, appetite, and so forth. Then one day we may look up and not recognize the person we’ve become.
  2. In a similar way, the various depression symptoms often don’t arrive at the same time. If depression symptoms all showed up together, landing in your life with a “THUD,” you’d probably know you were depressed. But the onset of depression can be more insidious—we develop a symptom here, a symptom there…. Maybe we don’t have as much energy as we used to, and a few weeks later we notice we’re more irritable toward our loved ones. We may not connect the two experiences to the same underlying condition.
  3. Depression varies greatly from person to person. Joe’s depression could involve feeling down, trouble sleeping, no appetite, problems concentrating, and thoughts of ending his own life. Jan’s, on the other hand, may include a lack of interest in anything, sleeping 14 hours a day, grinding fatigue, feelings of worthlessness, and being physically slowed down. So two people can both have major depressive disorder and have zero symptoms in common. If our symptoms aren’t ones we associate with depression, we’re less likely to think of ourselves as depressed. There are also varying degrees of depression; some people may find themselves stopped in their tracks by the condition, while many others are still able to go to work, laugh with friends, and take care of their home. While we don’t want to call every bout of sadness a “disorder,” we don’t have to be bedridden and suicidal to be depressed.
  4. Some symptoms might not seem like depression. We tend to think of “feeling blue” when we think of depression, and yet we can be depressed without feeling sad. We might feel more numb than sad, or just have no interest in things we used to enjoy. Some symptoms can be easy to attribute to other factors, since depression isn’t the only possible explanation. For example, we might blame our increased appetite and sleep problems on stress, and our trouble concentrating on our poor sleep.
  5. There may be no apparent “reason” to be depressed. Our moods can tank without a cause that we’re aware of. Maybe we’re genetically prone to depression, or sensitive to seasonal shifts. Or perhaps our lives have changed in ways that affect our mood and we didn’t make the connection. For example, we may have moved, leaving behind friends from our old neighborhood. Although we may be happy with our new location, we might be cut off from the social contacts we took for granted where we lived before. Without an obvious trigger for our depression, we’re less likely to see it when it comes.
  6. There may be a very apparent reason for feeling down. On the other hand, we might not call what we’re feeling “depression” because we expect to feel poorly, given our situation. If we’re going through a really hard time like losing our job, having major health problems, or a painful divorce, we don’t expect to feel as cheery as usual. These kinds of losses and challenges often lead to depression, as we lose reliable sources of reward, engagement, and support.
  7. I don’t want to see myself as someone who’s depressed. Finally, we might not recognize our own depression because we don’t want to. We may have internalized the stigma against depression, seeing it as a weakness or personal failing. Maybe we prided ourselves on our resilience and equanimity, and the notion of “I’m depressed” just doesn’t square with our identity.

The challenge of seeing our own depression can extend even to those who specialize in treating it, as I learned from personal experience. Early in my career I had gradually fallen into a depressed state that included a very negative way of seeing myself. I didn’t recognize the self-loathing as a symptom of depression; I just thought I was a loser.

Thus my depressed way of thinking didn’t announce itself, but instead masqueraded as reality. (Thankfully it turned out I wasn’t actually a loser.) Once I saw my depression for what it was, I understood where those negative thoughts were coming from.

Does it matter if we label our experiences as “depression”? I think it does, for at least two reasons.

First, by putting several difficult symptoms under a single umbrella, it can make them more manageable. Rather than having 15 problems, we have one: depression. And we need to simplify our challenges more than ever when we’re depressed.

Second, the label gives us a better idea of how to treat it. Several psychological treatments—”talk therapies”—have strong research evidence for alleviating depression. For example, a few weeks of cognitive behavioral therapy (CBT) generally has a big effect on depression symptoms.

There are also medications that are used to treat depression, some of which can even be as effective as the best psychotherapies.

If you or a loved one has been struggling lately and some of your symptoms could reflect depression, it may be a good idea to schedule an appointment with your primary care doctor or a mental health professional. The Association for Behavioral and Cognitive Therapies offers a searchable database for therapists who provide CBT, which is available here.

Whether we combat depression through self-help treatment or with a professional, we don’t have to suffer—help is available. And as with so many things, knowing what we’re dealing with is half the battle.