Depression is a serious mental health condition that can take many forms and affect people in wildly different ways. Often, depression is an invisible illness, meaning it can cause life-disrupting symptoms that aren't always obvious to others.

Beyond this, a person may not even realize they are experiencing depression symptoms because they believe the effects are natural or they are still able to perform most of their daily activities. Sometimes, people refer to this as “high-functioning” depression.

Sleep Changes

Some of the most notable symptoms across the different manifestations of depression are sleep disturbances. In fact, the issues are so interconnected that doctors may hesitate to even diagnose depression if a person does not have sleeping problems.

People with depression can struggle to fall asleep or stay asleep. They can also experience excessive daytime sleepiness. If someone does not realize they have depression, they may assume the sleep disturbances are natural or that they are just experiencing a random bout of insomnia or a bit of fatigue.

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Seeming “Lazy”

Another hallmark symptom of depression is a loss of interest or motivation. Hobbies that previously held a person’s attention no longer seem appealing, and they may even lose the drive to perform daily tasks like cleaning or going to work.

From the outside looking in, this may come across as laziness. However, lack of motivation could be a sign of a major mental health issue that requires treatment, not a personal failing.

Exhausted young man came home after work flopped down on sofa Viktoria Korobova / Getty Images


Moving or Talking Slowly

While most people associate depression with feeling “down,” its effects are far more complex. Depression can affect mental capacity in several ways, including the literal ability to think, harming the brain’s ability to process information and make decisions.

Experts refer to these functions as cognitive flexibility and executive functioning. Though many of these changes are subtle, some of the more noticeable include reduced reflexes and moving or talking slowly.

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Loss of Memory and Focus

Alongside the impacts on cognitive ability, depression can also cause memory loss and a drop in attention span. These symptoms may not even be that noticeable at first. A person could catch their mind wandering more than it usually does, or they may make simple errors with tasks they typically perform well.

Many people forget appointments, need to reread material multiple times, or immediately forget something they just learned. Without treatment, these issues can become more severe.

Bored unmotivated diverse Caucasian men feeling lack of interest during meeting. Sleepy worker feeling tired at lecture. Dissatisfied colleague looking at low energy man after meeting over Butsaya / Getty Images


Feelings of Worthlessness or Guilt

When it comes to depression, the symptom most people recognize is feeling “down” or sad. However, these words do not fully describe the weight of depression in most cases. For many people, depression comes with a debilitating feeling of guilt or worthlessness, often without a clear source.

These sensations can feed other symptoms, either triggering them or causing them to worsen.

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Even Minor Social Withdrawal

Mental health conditions, including depression, frequently involve some level of social withdrawal. This can range from full-on avoidance of social gatherings to something as small as not talking as much with friends.

The latter is particularly common among people with high-functioning depression. While they may still hang out with friends and family, they may not be as talkative or social as they were previously.

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Appetite and Weight Changes

Beyond the cognitive and emotional effects, depression can also impact a person’s diet and appetite. How this manifests is different for each individual. It is typical for depression to cause a lack of appetite, leading to undesired weight loss.

However, the opposite is also true. For some people, depression drives food cravings and a desire to snack, which then results in unwanted weight gain. These fluctuations can make other symptoms worse, causing a cyclical effect.

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Bleak Thoughts About the Future

Pervasive negative thoughts are a typical part of depression. However, experts note that in cases of high-functioning depression, these feelings often involve the future rather than current or past actions. Not only do people with depression tend to think about possible threats or dangers, but they also tend to believe that positive outcomes are much less likely or common.

Some studies indicate that this pattern of thinking is more common in older adults, though it can develop in anyone with depression.

Upset woman sitting on couch alone at home fizkes / Getty Images


Feeling Irritable, Angry, or Anxious

A person who does not realize they have depression may recognize the condition if they find themselves feeling angry, irritable, or even anxious without a clear reason. Commonly, depression triggers volatile mood swings where the mood fluctuates from mild irritability to extreme sadness to angry outbursts within a short period.

Young man getting angry on the road ozgurcankaya / Getty Images


Persistent Thoughts of Death or Suicide

Among the potential changes in thought processes with links to depression, some of the most dangerous are ongoing preoccupations with death and suicide. These are not fleeting or intrusive thoughts but are instead persistent and complex thought processes.

They may or may not involve a plan to follow through. When these thoughts occur, it is important to recognize them for what they are and reach out to a professional for help.

Asian man with mental disorder sitting alone late at night and feeling paranoid. Mixed race man mentally ill, feeling depressed and crying in his bedroom at home. Insomniac feeling scared and hopeless PeopleImages / Getty Images


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This site offers information designed for educational purposes only. You should not rely on any information on this site as a substitute for professional medical advice, diagnosis, treatment, or as a substitute for, professional counseling care, advice, diagnosis, or treatment. If you have any concerns or questions about your health, you should always consult with a physician or other healthcare professional.