I see so many questions and comments in my private group about sweating, in particular, ‘night sweats’ and it’s prompted me to dig deeper, thus this article.

When I look at a dozen decent sources of medical info, they all seem to bring up several common causes appearing on the different lists on each website I look at. I do see (so-called) carcinoid syndrome come up infrequently and perhaps the authors are lumping that in with hot flashes/flushing etc.  But on authoritative NET sites (i.e. written by the NET scientific community), I do not see ‘sweating’ come up in the list of known symptoms directly attributed to any of the syndromes except for the group of catecholamine secreting tumours known as Pheochromocytoma and Paraganglioma

I decided to extend it to diet because diet can be involved, and late eating may result in night sweats (technical name – sleep hyperhidrosis). One site, Medical News Today, indicated around 3% of the population suffers from this condition.

My research indicates that sweating and in particular night sweats, need to be well defined. Most sites I looked at seemed to provide a definition along the following lines – Night sweats refer to excess sweating during the night. True night sweats are severe hot flashes occurring at night that can drench your clothes and sheets and that are not related to an overheated environment. It’s important to note that flushing (a warmth and redness of the face or body) may be hard to distinguish from true night sweats. Mayo Clinic described them as “repeated episodes of extreme perspiration that may soak your nightclothes or bedding and are related to an underlying medical condition or illness“. Mayo went on to say night sweats are also associated with fever, weight loss, localized pain, cough, diarrhea, or other symptoms of concern. Most sites took some time to differentiate between bedrooms that are unusually hot, or the person is wearing too many bedclothes, resulting in sweating during sleep, this is normal.

As I said above, I studied several well-known medical sites and came up with many similar potential reasons – interestingly I see many of these potential connections in my private group too – but I make no effort to make assumptions, I want to make readers aware of these potential connections so they can assess themselves and if necessary, seek medical advice.

For night sweats as defined above, I short-listed the following causes because they tended to appear in most lists covering the topic, and though it might help you look closer for the causes of why it’s happening to you. Some sites have huge lists, so I only listed the ones I saw on several sites indicating these are more prevalent causes. Also, please don’t assume I’m suggesting any of these is the cause of what you are experiencing or have added above. I’m conscious that some of you may have had a late diagnosis due to carcinoid syndrome flushing being blamed on menopause but it has to be included because it is a known symptom. 

1. Menopause symptoms (“hot flushes”). Menopausal flushes are recorded by many sources as the most common cause of night sweats. Usually, involve the whole body and might be related to the release of calcitonin gene-related peptide (CGRP) with transient vasodilation, a so-called dry flush. Another type of menopausal symptom is the wet flush, which includes epinephrine-induced sweating. Proposed mediators of flushing in menopause are CGRP, histamine, prostaglandins, serotonin, lysyl-bradykinin, and substance P. Estrogen is known to have an impact on the production and release of different signalling substances such as noradrenaline and β-endorphin. Low estrogen levels cause lower β-endorphin activity, which in turn enhances the release of gonadotropin-releasing hormone (GnRH), which gives rise to high luteinizing hormone (LH)levels. Postmenopausal women in whom a true carcinoid syndrome is developing can tell the difference between the two types of flushes. Source – Endocrinology: Adult and Pediatric – 7th Edition 2016 Chapter 151 – Carcinoid Syndrome – authored by Kjell Oberg International NET specialist.

WebMd stated “Hot flashes” before and after your final period can be hard to distinguish from night sweats. Younger women who’ve had both ovaries removed or who stopped menstruating because of chemo can also get them. They’re more likely to happen when you’re anxious, depressed, or have a drink every day. But just because you’re a woman of the right age (typically, in your late 40s or 50s), don’t assume your night sweats are menopause-related.

I also wanted females to read this article from Harvard Health which stated that for many women, hot flashes and night sweats often last seven years and may go on for 11 years or more. Click here to read.

2. Anxiety disorders. Behaving anxiously activates the stress response. The stress response immediately causes specific physiological, psychological, and emotional changes in the body that enhance the body’s ability to deal with a threat – to either fight with or flee from it – which is the reason the stress response is often referred to as the fight or flight response. Part of the stress response changes includes increasing the body’s metabolism, respiration, and perspiration. This is why the heart beats harder and faster, our breathing changes, and we have a tendency to sweat when we are anxious. If you worry in the middle of the night, the active stress response worry triggers could be the reason for your night sweats. Source – The Anxiety Centre.  Listed as one of 16 major causes by WebMD and on Mayo Clinic’s list of 20.

3. Medicines – some antidepressants, steroids and painkillers. Taking certain medications can lead to night sweats. Antidepressant medications are a common type of drug that can lead to night sweats. From 8% to 22% of people taking antidepressant drugs have night sweats. Other psychiatric drugs have also been associated with night sweats. Medicines taken to lower fever, such as aspirin and acetaminophen, can sometimes lead to sweating. Many other drugs can cause night sweats or flushing. Source – WebMD. I do note a significant number of people taking antidepressants in the community. Mayo Clinic lists “Hormone-blocking drugs” as a cause although they don’t elaborate on which ones. However, the inference is medications that stop the body from making estrogen after menopause.

4. Low blood sugar (hypoglycaemia) and drugs used to treat diabetes (hypoglycemic agents). Low blood sugar can cause sweating. People who are taking insulin or oral diabetes medications may have hypoglycemia at night that is accompanied by sweating. Source – WebMD. Many people do have these issues due to Neuroendocrine Cancer plus others may experience this as a side effect of their treatment, e.g. somatostatin analogues.

5. Diet – I wanted to bring diet into the equation. This is somewhat an extension of the low blood sugar issue above if people are eating or drinking late which may be leading to night sweats.

• It’s not uncommon to sweat when you eat hot or spicy foods. If eating or drinking a specific food raises your body temperature, then your body will try to cool itself by sweating. Source – WebMD
• Sometimes, a high-sugar meal can cause your body to make too much insulin, the hormone that helps you process sugar and change it into energy. That can lead to a dive in blood sugar known as reactive hypoglycemia. Sweating is one sign of that. Source – WebMD
• “Meat Sweats”. I’ve heard of that, and I’ve even said it without realising what it meant. There isn’t extensive research on meat’s effect on sweating. What is known is that digestion takes up about 25% of our energy, and protein requires more energy than other foods to digest. Proteins are extremely complex molecules and require a lot more energy than fats or carbohydrates to metabolize. If you’re eating a lot of protein, your body will be producing a lot of energy and a lot of heat. Of course, this could result in sweating. Source – Healthline

6. Drug addiction (substance use disorder) or withdrawal (alcohol, opioids, cocaine, cannabis, benzodiazepines). Known to cause chills and sweating. Source – Mayo Clinic

7. A harmless condition called hyperhidrosis that makes you sweat too much all the time. Idiopathic hyperhidrosis is a condition in which the body chronically produces too much sweat without any identifiable medical cause. Source – WebMD

8. Infections can trigger night sweats. A known side effect of Tuberculosis. Some infections like bacterial endocarditis (infection of the inner lining of your heart and heart valves) and osteomyelitis (bone infections) can cause it. There are other rarer infections that can cause night sweats as well and your doctor will check you for them based on your risk factors, exposure and travel history. Source WebMD.

9. Cancer – sites mostly list Lymphoma and Leukaemia which are known to have this symptom (please note these cancers have many other symptoms other than night sweats so don’t panic). WebMD lists Prostate cancer, kidney cancer, and some tumors in the ovaries and testicles (both cancerous and not) are common examples of what doctors call “solid tumors” that can cause night sweats. Clearly, there is the issue of (so-called) carcinoid syndrome where flushing at night might appear to be night sweats as indicated above and both WebMD and Mayo Clinic added it to their lists. Also, worth mentioning functioning Pheochromocytoma and Paraganglioma where the release of excess catecholamines (adrenaline hormones) results in the classical triad of symptoms of heart palpitations, sweating, and headache. This was also listed by WebMD and Mayo Clinic.

10. Gastroesophageal reflux disease (GERD): The primary symptom is heartburn, but night sweats are also a common feature. It’s not only the heartburn and chest pain that can wake you up. GERD hasn’t been studied much as a cause of night sweats, but doctors say there’s a possible connection. And treating it can often ease your night sweats. Source – WebMD. Worth noting that some Neuroendocrine Cancer patients have this as part of their syndromes, e.g. Gastrinomas. Also, I do note many people have this as a pre-existing condition and it’s one of the most common conditions in the general population in varying degrees.

11. Obstructive sleep apnoea. When you have this condition, you briefly stop breathing over and over during the night. Because your body isn’t getting oxygen, it may slip into “fight or flight” mode, which triggers sweating. Each time it has to kick-start breathing means a burst of work from your muscles, too. People who use a CPAP machine to help them breathe at night have night sweats about as often as those who don’t have sleep apnoea. Source – WebMD. Mayo Clinic concurred.

12. Thyroid issues, hyperthyroiditis is commonly mentioned. Sweating more and being sensitive to heat are notable symptoms of hyperthyroidism. (overactive thyroid). Your thyroid gland controls your metabolism, so when it makes too much hormone, your body goes into overdrive. Your body temperature rises, and you could be hungrier or thirstier, have a racing pulse or shaking hands, feel tired and out of sorts, get diarrhea, and lose weight. Source – WebMD

13.  Peripheral Neuropathy.  Peripheral neuropathy, a result of damage to the nerves outside of the brain and spinal cord (peripheral nerves), often causes weakness, numbness and pain, usually in your hands and feet. It can also affect other areas of your body.  Peripheral neuropathy can result from traumatic injuries, infections, metabolic problems, inherited causes and exposure to toxins. One of the most common causes is diabetes. Signs and symptoms of peripheral neuropathy where autonomic nerves are affected might include excessive sweating (or not being able to sweat).  Source – Mayo Clinic.

Summary

Despite the big list above, some sites also stated the cause of night sweats is unknown. I hope this has been useful for some. A reminder that this is not intended as medical advice (see my disclaimer below), just sharing my research into the causes of night sweats.