10 Serotonin Deficiency Symptoms Everyone Should Look Out For

Woman standing outside, looking thoughtful while she holds a coffee cup.Serotonin is a neurotransmitter that plays a role in behavior, mood, movement, learning, and many other functions. Its technical name is 5-hydroxytryptamine or 5-HT. Like all neurotransmitters, serotonin carries a nerve signal across a synapse.

When serotonin levels are too low, this can weaken nerve signals. One of the most common symptoms of low serotonin is depression, but low serotonin levels can affect almost every system of the body, leading to a wide range of symptoms.

Understanding Serotonin: What Does Serotonin Do?

Researchers have studied serotonin for more than 60 years and uncovered roles for this important neurotransmitter in numerous brain functions. All animals and even plants produce serotonin, suggesting it appeared very early in evolution.

Yet serotonin is difficult to isolate. Moreover, a wide range of neurotransmitters—as well as other factors, such as a person’s overall health, environment, and unique biology—can affect mental and physical health. This has made it difficult for researchers to establish direct correlations between serotonin and various functions.

Researchers have long thought serotonin deficiency can lead to depression. In fact, many popular antidepressants increase brain serotonin levels. Yet some studies throw even this widely accepted theory of serotonin into question. A 2014 study of mice, for example, found that genetically lowering serotonin levels did not lead to depression. Clinicians have long theorized that serotonin levels are genetically low in some people with depression, so this study undermines that theory.

Numerous ailments can cause symptoms of serotonin deficiency, so it’s important to see a health care provider to get an accurate diagnosis and appropriate treatment.

This mixed research means it is impossible to diagnose serotonin deficiency based on symptoms alone. People with normal serotonin levels may experience symptoms consistent with serotonin deficiency, while some people with low serotonin may have no symptoms at all. Numerous ailments can cause symptoms of serotonin deficiency, so it’s important to see a health care provider to get an accurate diagnosis and appropriate treatment.

What Causes Serotonin Deficiency?

Most cases of serotonin deficiency are idiopathic, meaning doctors are unable to find a specific cause. Some inherited genetic disorders may affect the body’s ability to make or metabolize serotonin. Lifestyle and other factors that may also play a role include:

  • Hormonal shifts, such as due to beginning or stopping hormone replacement therapy, menopause, pregnancy, or advancing age
  • Lack of sunlight
  • Poor nutrition
  • Certain drugs and medications, especially when used to excess or over a long period of time
  • Chronic stress

10 Serotonin Deficiency Symptoms

Serotonin never acts alone, and it’s part of a complex system. People with serotonin deficiency may also have deficiencies in other neurotransmitters, as well as metabolic or other health problems. Some common signs of serotonin deficiency include:

1. Depression

Research increasingly points to a complex relationship between depression and serotonin. We don’t fully understand how serotonin deficiency can cause depression, but most studies argue that it is a factor. Depression related to life events, especially chronic stress and trauma, may also deplete serotonin levels. So serotonin deficiency can be both a cause and a result of depression.

2. Changes in sleep

Serotonin helps regulate the body’s internal clock, including the ability to feel sleepy, remain asleep, enter rapid eye movement (REM) sleep, and wake in the morning. People with chronic insomnia, unusual sleep patterns, chronic fatigue, or consistently vivid dreams may have serotonin deficiency.

3. Chronic pain

Serotonin affects the way the muscles behave, so low serotonin may cause chronic pain. Low serotonin is strongly correlated with fibromyalgia, a type of widespread chronic pain. People with fibromyalgia may even get relief from antidepressants that raise serotonin levels.

4. Memory or learning issues

Some studies have linked serotonin to memory and learning, so sudden difficulties with memory or learning could signal a serotonin issue. Additionally, other symptoms of serotonin deficiency, such as sleep deprivation and depression, can make it difficult to concentrate and learn.

5. Anxiety

Anxiety, including obsessive-compulsive forms of anxiety, may indicate a person has low serotonin. Anxiety that comes on suddenly and appears unrelated to something else, such as a recent trauma or stressor, is often due to a serotonin issue. Chronic stress and anxiety may also deplete serotonin.

6. Schizophrenia

Many studies have found low serotonin levels in people with schizophrenia. Unusual beliefs or behaviors, auditory or visual hallucinations, and sudden changes in mood or personality may be a sign of low serotonin.

7. Problems with the body’s internal clock

Serotonin helps regulate the body’s circadian rhythm, which is its internal clock. Though it’s common for people to have difficulties getting up in the morning or occasionally forget meals, dysregulation in the internal clock can cause serious sleep, appetite, and other issues. A person who never sleeps according to a regular schedule, who has difficulty maintaining a consistent pattern of hunger and eating, or who feels chronically tired or hyper could have a problem with their circadian rhythm. This may be due to low serotonin.

8. Appetite issues

A number of studies have found that people with low serotonin may have appetite issues or eating disorders. This may include overeating, not eating enough, or alternating between the two. Additionally, some people with depression also experience problems with appetite.

It’s possible for a person whose blood serotonin levels appear normal to have very little usable serotonin.

9. Hyperactivity

Low serotonin can cause symptoms of attention deficit/attention-deficit hyperactivity (ADD/ADHD). A person may have trouble concentrating, constantly fidget, be chronically bored, or be unable to sit still. Children may appear to have boundless energy, behave aggressively, or frequently get into trouble at school.

10. Dementia

A handful of new studies suggest that low brain serotonin is linked to dementia and may even be an early warning sign of this group of diseases. It’s unclear if the low serotonin causes dementia or is a symptom. Because serotonin can affect memory, concentration, and other cognitive functions, however, it’s possible that drops in serotonin increase the risk of dementia as a person ages.

Serotonin Deficiency Diagnosis and Treatment

A serotonin blood test can measure levels of serotonin in the blood. However, doctors usually only use this test to check for serotonin-producing tumors. Doctors don’t usually perform blood tests to assess serotonin levels because factors other than blood serotonin—such as metabolism, the behavior of serotonin receptors, and hormones—can affect the body’s ability to process and use serotonin. It’s possible for a person whose blood serotonin levels appear normal to have very little usable serotonin.

Instead of testing serotonin levels, doctors typically treat a person’s symptoms. Depending on the symptoms you have, your provider may recommend tests to rule out other causes, such as hormone imbalances or a physical injury. Then they may recommend a medication that raises serotonin levels, such as an antidepressant. In some cases, providers may also recommend lifestyle changes such as exercise.

Serotonin deficiency is a complex issue. Lifestyle and psychological factors often play a central role. Moreover, symptoms of serotonin deficiency can affect a person’s relationship and quality of life. Therapy can help in numerous ways. For people with depression related to low serotonin, a therapist can offer lifestyle management tips, a sympathetic ear, and help with relationship issues.

Therapy can also help people with low serotonin become better advocates for themselves. For example, a person with fibromyalgia or chronic pain may struggle to talk to loved ones about their symptoms or feel reluctant to request accommodations at work. Therapy can help them explore their options, adopt healthy self-care strategies, and advocate for their needs.

For help finding a therapist who can support you as you deal with low serotonin, click here.


  1. Al-Nimer, M. M., Mohammad, T. M., & Alsakeni, R. (2018). Serum levels of serotonin as a biomarker of newly diagnosed fibromyalgia in women: Its relation to the platelet indices. Journal of Research in Medical Sciences, 23(1), 71. doi: 10.4103/jrms.JRMS_859_17
  2. Angoa-Pérez, M., Kane, M. J., Briggs, D. I., Herrera-Mundo, N., Sykes, C. E., Francescutti, D. M., & Kuhn, D. M. (2014). Mice genetically depleted of brain serotonin do dot display a depression-like behavioral phenotype. ACS Chemical Neuroscience, 5(10), 908-919. doi: 10.1021/cn500096g
  3. Brain scan study adds to evidence that lower brain serotonin levels are linked to dementia. (2017, August 14). Retrieved from https://www.hopkinsmedicine.org/news/media/releases/brain_scan_study_adds_to_evidence_that_lower_brain_serotonin_levels_are_linked_to_dementia_
  4. Frazer, A., & Hensler, J. G. (1999). Serotonin. In G. J. Siegel (Author), Basic neurochemistry: Molecular, cellular and medical aspects (6th ed.). Amsterdam: Elsevier Academic Press.
  5. Whitney, M. S., Shemery, A. M., Yaw, A. M., Donovan, L. J., Glass, J. D., & Deneris, E. S. (2016). Adult brain serotonin deficiency causes hyperactivity, circadian disruption, and elimination of siestas. Journal of Neuroscience, 36(38), 9828-9842. doi: 10.1523/JNEUROSCI.1469-16.2016

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  • Leave a Comment
  • Andrew

    July 30th, 2019 at 1:21 AM

    I battle anxiety for 30 years without knowing it and in 2015 iwas generally petigue , and fear took control of my life. I feel hopeless because all the test was Ok and I was confused. One day an old Dr. Put me on C8pramil (Citalopram) and it helped me to regain my strength however due to having 5he problem many years I’ve trouble sleeping .I used to have very bad dreams at night times and go to pee often at nights. However when I take Citalopram no dreams and I slept well so please help me fully recover to live normal lives. I would appreciate your help .
    God Bless .

  • anoninmous7

    August 25th, 2019 at 6:07 AM

    See a specilist , to get checked to see if you have Fibromyalgia. Im researching more about it was diagnosed 2-3 days ago. i think its problems in the Decending pain pathway wich aperntly acording to Google ,what helps the Decending pathway as in pain , is Serotonin – aparently low Serotonin can cause pain. and well Fibromyalgia is also known as Chronic pain Disorder. has many symptoms too.

  • Anonymous

    March 10th, 2020 at 2:47 PM

    Andrew made no comments re: pain so why would you shotgun fibromyalgia? Not good advice.

  • Anonymous

    March 10th, 2020 at 2:49 PM

    Andrew, you might want to have thyroid testing done (pretty standard) and also given urinary frequency symptoms, you might want to see a urologist to see what the cause might be, UTI, prostate issue, etc. Another option could be adrenal related (addisons or cushings depending on your cortisol, etc. ) levels.

  • Carlene

    September 2nd, 2019 at 12:51 PM

    Can having a sleep disorder affect someone temperament. Or response behavior

  • Gustaf

    May 15th, 2020 at 12:50 PM

    Yes, problems with sleep can cause bad response behaviour and affect the temperament in long term.

  • Helen

    July 4th, 2020 at 6:00 PM

    Since the Virus 19 started in the new year my stomach has been chronic, eating and digestive problems in my stomach, which I have always had trouble with when I have Anxiety, thought with this virus going on forever it’s a problem, with sleep, just 3 to 4 hours a night then sleeping daytime! I have had a stomach band fitted but always had trouble with bad digestive after it so finally go all the band deflated, it is still in place though, and wondering if this is causing some of my problems ? My anxiety is high with all this virus 19 etc., I have taken antidepressants for a long time now, IAm coming up to 73 years old next month! I have an unbiblical hernia also!
    I feel really very very sad with worry about this Virus 19 , I’ve two wonderful grandchildren and I worry so much about everything for them, always seem to be very sad and wondered if my serotonin is too low or something. I always feel happy for everyone else , so that’s not a problem. Just hoping you can give me so directions to go in, it’s hard to ask for help at the busy doctors because they are working so hard and it’s takes a lot of time keeping up to date with doctors appointments because my kidney aren’t working so good either! I feel so bad bothering everyone with my problems, thank you .

  • Willis

    July 27th, 2020 at 1:38 PM

    Don’t do anything rash, Helen! I am not a doctor*, but if I were you I’d keep taking care of my kidneys and do everything as usual, but add in some mindfulness training. Turn off the news, the TV, and anything else that reminds you or informs you of the virus. Have someone else who is in a better state of mind call you and let you know of any important updates like if new protocols are being put into place or new things are opening up, etc. Do not have them inform you of bad news. Eating up the bad news right now is not going to help anyone, and just hurt you! Covid 19 will be temporary, and often medications in this realm are difficult to get off of.

    P.S. Happy 73rd Birthday!

    *I am not a doctor or mental health professional. My comments are not a substitute for professional medical or mental health advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical or mental health condition.

  • Johanna

    August 13th, 2020 at 2:20 PM

    For those with Fibromyalgia, I was diagnosed with Fibromyalgia in 1997 and have struggled with it for years. I was initially put on a 600mg of Nsaid and my stomach couldn’t handle it. I found a new DR and asked what I could take for pain that wouldn’t be so hard on my stomach and he prescribed Tramadol. I have been using it ever since. I have never taken more than a dose of 50mg which is the lowest dose available. At first I was taking one each day and was able to work, help care for my youngest grand child and be mostly pain free. I am now experimenting to see how low a dose I can use and still be functional. I have cut the 50mg tablets in fourths and depending on how much pain or how I anticipated the intensity of the day ahead, I can get by on 1/4 a tab which is a 12.5mg dose. I believe that, for me , Fibromyalgia is largely an effect of serotonin deficiency and a low dose of Tramadol can effectively help reduce pain and improve energy levels. My doctor has worked with me through out this process and is very open minded. I don’t know if this could help anyone else, but you might ask your doctor about Tramadol as a way to help with Fibromyalgia symptoms. Tramadol can be addictive so caution is necessary.

  • Andrew

    September 24th, 2020 at 5:44 PM

    I am a little shocked that in your causes of low serotonin that you did not mention alterations to the microbiome and gut health. I feel this is a serious omission as it is believed that as much as 90% of the bodies serotonin is produced by your microbiome.

  • Sudarshana

    December 22nd, 2020 at 1:09 AM

    Hi Helen,
    I am a counselling psychologist from India. Exposure to sunlight,bright white light in rooms,exercising a bit,eating nutritious food increases Vit D levels too.. that helps bring back serotonin levels to normalcy.. Low serotonin levels bring depression… Loud singing,chanting and gargling help stimulate your vagus nerves around the neck.. that can bring depression down.. pls try these🙂

  • Julie

    January 15th, 2021 at 7:10 PM

    I’m 55 and have Severe Anxiety. I don’t like taking benzos. What can I do?

  • Dan

    January 21st, 2021 at 2:40 PM

    Hi guys i am little confused as to what i have, for about nearly 2 years i have been unwell. I had a stressful event in my life which has now past and i am over it but my brain seems to be stuck with it.
    -lack of libido(male)i dont get excited enjoy sex
    -i dont see dreams anymore
    -sleep was an issue but its has come back.
    – i dont enjoy events which used to excite me like movies,outing
    i have been to the doctors done blood work testesterone etc came back normal including other harmones. Doctors were not helpful so i have booked a physiatrist to see early march.
    Any supplements i can take in the meantime? thanks in advance.

  • Andrew

    March 2nd, 2021 at 3:20 PM

    I had a slight pain on the right lower part of my rectum, when I was 24 and I battle for 30 years and medication did not help . I was really down and fear of fainting or dying took control of my life. One day a Physician put me on 5mg of Alprazolam for 30 day and it has drustically improved my condition and soon after put me on Cipramil and I went back normal ,however when I quit taking Cipramil , I develop sleep problem. Had frequent night Mares and it’s affecting me and therefore needs help advise to go about it.
    I would appreciate if one expert can advise on how to deal with this problems.

  • Alejandra

    April 21st, 2021 at 9:33 AM

    Try citaloprahm, i have heard a lot of good things about it, try asking your doctor or researching online

  • Ale

    April 21st, 2021 at 9:34 AM

    Citalophram , I heard it’s good

  • One

    June 10th, 2021 at 6:25 AM

    Hello. I have been with these anxiety and depression for 5 yrs, since 2017. But I only started taking meds since 2019, bcs things start getting more serious at tht time. Until end of 2019, I stop taking the meds, bcs i felt like it affect my work performance. I often feel sleepy at work, and my body feel so weak. I still managed to control it without meds, until feb 2020, the rush and uneasy feelings, is coming back. I still have my meds, (the one i got frm the hosp in early 2019), and sometimes, when I am out of control, I take one.
    For now, I;m still taking those meds, but sometimes i think the meds doesnt help at all. why ?

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