What Causes a Dry Mouth at Night, and What Can I Do About It?

Wondering why you wake up in the morning with a dry mouth?  This article covers the reasons your mouth could feel dry at night and solutions you can use to help keep your mouth moist when you sleep.


Why does your mouth feel dry?

Dry mouth, also known as xerostomia, is the feeling of dryness in your mouth.  You might be experiencing dry mouth if your salivary glands aren’t producing enough fluid to keep your mouth wet. 

Dry mouth can be caused by lots of different factors, including dehydration, other health conditions, eating the wrong foods, and certain types of medication.  If you live with persistent dry mouth, you might struggle to perform everyday tasks like speaking, swallowing, and eating. 


Causes of Dry Mouth at Night and What You Can Do to Make It Better

Let’s take a look at the different causes of dry mouth at night, and what you can do to counter them.


Natural Saliva Flow Reduction

The most common reason our mouths dry up at night is pretty simple: our bodies naturally produce less saliva when we’re asleep.  Saliva flow rate isn’t a constant – it peaks during mid-afternoon, and drops to extremely low levels when our sleep hormones kick in [1].

The reason our bodies produce less saliva when we’re asleep is so we don’t have to swallow as often, making our nights much more restful [1]. 


There isn’t much you can do about your body naturally reducing your saliva flow at night.  If you keep waking up with an extremely dry mouth or throat, try putting a drink bottle next to your bed so you can sip water when you wake up. 

Alternatively, use a dry mouth spray like Osmist to coat the inside of your mouth – two quick pumps delivers up to three hours of relief, and you won’t need to keep getting up to go to the bathroom.


Breathing with Your Mouth Open

Although breathing with your mouth open won’t actually reduce the amount of saliva your body produces, it can increase the rate your saliva evaporates at [2].  Some surfaces of your mouth, like your hard palate (the roof of your mouth), lose saliva faster than other places [2].

The end result?  Mouth-breathers often wake up with dry mouths and bad breath (a common side-effect of xerostomia). 


Mouth breathing during sleep can be symptomatic of – or even cause – a number of different health conditions, including nasal blockages and sleep apnea [3].  Consequently, it can be a good idea to fix up your nocturnal breathing habits, even if you don’t think they’re the cause of your dry mouth.

Here are a couple of ways you can prevent mouth breathing and promote nasal breathing:

  • Use nasal decongestants if your nose is blocked by cold or allergy symptoms
  • Buy a good pillow that supports your head properly.  If your head is too far back, you’ll end up breathing through your mouth.  If your head is propped up too high, you’ll constrict your throat and struggle to breathe.
  • Use nasal dilators (adhesive strips applied to the bridge of your nose), which can help you breathe through your nose more easily.
  • Consult a sleep specialist.  Healthcare professionals who specialise in sleep disorders will be able to properly diagnose the cause of your mouth breathing and help you find an appropriate solution.


Being Dehydrated

Being dehydrated is one of the most common causes of oral dryness.  Saliva is 99% water, so it makes sense that if you’re not drinking enough, your mouth won’t be able to stay properly moist. 

A large body of scientific evidence has definitively linked dehydration to dry mouth [4].  Interestingly, studies have also shown that reduced unstimulated salivary flow rates can continue even after dehydrated individuals have been rehydrated, indicating that ‘full’ rehydration of the salivary glands may take longer than general rehydration [5].     


Dehydration is one of the easiest causes of dry mouth to fix.  Just drink more water! 

While recommendations vary for the amount of water you should drink each day, the US National Academies of Sciences, Engineering and Medicine recommends approximately 2.7 litres of water each day for women, and 3.7 litres each day for men.  If you live in a hot climate, work in a physically active job, or engage in lots of exercise, you might need to drink more than that.  An estimated 20% of your daily intake of water comes from food – the other 80% is from pure water and various beverages.       


Dry, Cold Night Air

Very dry or cold night air can also make your mouth feel dry, and may even lead to your throat feeling sore.  Low humidity in the air means your saliva evaporates faster, which can cause xerostomia.

In Australia, having a dry mouth is common over winter, but you might also experience it over summer if you sleep with the air con running.


Using a beside humidifier is an easy way to increase the humidity of the air you’re breathing in, which helps reduce the evaporation rate of your saliva.  Even if your dry mouth is caused by medication or a health condition, a humidifier can relieve the severity of your symptoms, making overnight dry mouth easier to live with. 


Products That Cause Dry Mouth

Certain products, like alcohol, alcohol-based mouthwashes and tobacco, can make overnight dry mouth worse.

Studies have shown a statistically significant correlation between smoking tobacco products and xerostomia.  Although new smokers may actually have an increased salivary flow rate initially (thanks to their salivary glands being stimulated), smoking decreases salivary function over time [6].

One study found that 37% of surveyed smokers had dry mouth, compared to 13% of non-smokers [6].  Another study found the mean salivary flow rate was 0.38 millilitres per minute for smokers, while non-smokers had a rate of 0.56 millilitres per minute [7].

Alcohol and alcohol-based washes can also dry out your mouth.  Chronic alcohol intake can kill and damage cells that help produce saliva, damage the salivary gland tissue, and decrease overall saliva production [8]. 

While some studies have indicated that the short-term use (less than seven days) of alcohol-based mouthwashes is safe, most healthcare professionals recommend avoiding ongoing use of washes that contain alcohol if you have dry mouth [9].     


If possible, quit smoking and stop excessive drinking.  Both tobacco and alcohol can cause lasting damage to your salivary glands, resulting in persistent dry mouth.

You can find support for quitting alcohol here and quitting smoking here.

If you’re currently using a mouthwash that contains alcohol, switch to an alcohol-free wash instead.      

Medication and Health Problems

Dry mouth at night can also be caused by a wide variety of other conditions, including [10]:

  • Radiation treatment for cancer
  • Certain types of medication, including antidiabetics, antihypertensives and antidepressants
  • Trauma to the salivary glands
  • Pregnancy
  • Old age
  • Diabetes
  • Autoimmune diseases, like Sjögren’s syndrome, rheumatoid arthritis, scleroderma and primary biliary cirrhosis
  • Infections, like HIV, hepatitis C, Epstein-Barr virus and T-lymphotropic virus type 1
  • Other health conditions, like tuberculosis, graft-versus-host disease, kidney disease, hemochromatosis and Parkinson’s disease


If you think your overnight dry mouth could be the result of a health condition or medication, using a dry mouth spray like Osmist can deliver up to three hours of relief.

Osmist is enriched with three active natural ingredients: grapeseed oil, papaya enzymes, and peppermint oil.  Grapeseed oil acts as a lubricant, coating the inside of your mouth and making it easier to swallow, while papaya enzymes help stimulate saliva flow [11].

Unlike other dry mouth sprays, Osmist is free from harmful chemicals and potentially carcinogenic ingredients – it’s one of the safest, most natural ways to combat your overnight dry mouth.  Keep a bottle of Osmist by your bed, and pump two quick sprays into your mouth when you wake up.

The best part?  The natural peppermint oil in Osmist can help get rid of that unpleasant morning breath, making waking up better for both you and your partner.

You can purchase Osmist from your local chemist, or buy a bottle from our online store for easy home delivery.


Home Remedies for Dry Mouth at Night

Skipped to this section because you’re short on time?  Here’s a summary of the solutions to overnight dry mouth we talk about in the rest of the article.

  • Sip from a drink bottle next to your bed at night
  • Use techniques to help breathe through your nose instead of your mouth
  • Stay properly hydrated
  • Use a humidifier in your bedroom
  • Quit smoking and excessive alcohol consumption
  • Avoid alcohol-based mouthwashes
  • Use Osmist Dry Mouth Spray to relieve dry mouth for up to three hours


To find out whether your might have dry mouth, use our free dry mouth self-assessment tool.

If you have a persistent dry mouth, consult a healthcare professional like a dentist, speech pathologist or GP.

Medical information on is merely information and is not the advice of a medical practitioner. This information is general advice and was accurate at the time of publication. For more information about oral care and your individual needs, seek the advice of a qualified medical professional.




[1] Dawes, C., Pedersen, A. M. L., Villa, A., Ekström, J., Proctor, G. B., Vissink, A., Aframian, D., McGowan, R., Aliko, A., Narayana, N., Sia, Y. W., Joshi, R. K., Jensen, S. B., Kerr, A. R. & [2] Wolff, A. (2015) The functions of human saliva: A review sponsored by the World Workshop on Oral Medicine VI. Archives of Oral Biology. 60(6), 863–874. DOI: 10.1016/j.archoralbio.2015.03.004 

[2] Kleinberg, I., Wolff, M. S. & Codipilly, D. M. (2002) Role of saliva in oral dryness, oral feel and oral malodour. International Dental Journal. 52(S5P1), 236–240. DOI: 10.1002/j.1875-595x.2002.tb00932.x 

[3] Lavie, P. (1987) Rediscovering the importance of nasal breathing in sleep or, shut your mouth and save your sleep. The Journal of Laryngology & Otology. 101(06), 558–563. DOI: 10.1017/s0022215100102245 

[4] Greenspan, D. (1996) Xerostomia: Diagnosis and Management. Oncology. 10(3).

[5] Ship, J. A. & Fischer, D. J. (1997) The Relationship Between Dehydration and Parotid Salivary Gland Function in Young and Older Healthy Adults. The Journals of Gerontology Series A: Biological Sciences and Medical Sciences. 52A(5), M310–M319. DOI: 10.1093/gerona/52a.5.m310 

[6] Saddu, S. C. & Dyasanoor, S. (2014) Association of Xerostomia and Assessment of Salivary Flow Using Modified Schirmer Test among Smokers and Healthy Individuals: A Preliminutesary Study. Journal of Clinical and Diagnostic Research. 8(1), 211–213. DOI: 10.7860/jcdr/2014/6650.3846 

[7] Rad, M., Kakoie, S., Brojeni, F. N. & Pourdamghan, N. (2010) Effect of Long-term Smoking on Whole-mouth Salivary Flow Rate and Oral Health. Journal of Dental Research, Dental Clinics, Dental Prospects. 4(4), 110­–114. DOI: 10.5681/joddd.2010.028

[8] Inenaga, K., Ono, K., Hitomi, S., Kuroki, A. & Ujihara, I. (2017) Thirst sensation and oral dryness following alcohol intake. Japanese Dental Science Review. 53(3), 78–85. DOI: 10.1016/j.jdsr.2016.12.001 

[9] Nair, R., Chiu, S. E., Chua, Y. K., Dhillon, I. K., Li, J., & Yee Ting Fai, R. (2017). Should short-term use of alcohol-containing mouthrinse be avoided for fear of worsening xerostomia? Journal of Oral Rehabilitation, 45(2), 140–146. doi:10.1111/joor.12587 

[10] Millsop, J. W., Wang, E. A. & Fazel, N. (2017) Etiology, evaluation, and management of xerostomia. Clinics in Dermatology. 35(5), 468–476. DOI: 10.1016/j.clindermatol.2017.06.010 

[11] Rowe, M., Lawn, C. & Wilson, B. (2018) Effects of Papaya Enzymes in Patients with Dry Mouth. Acta Scientific Pharmaceutical Sciences. 2(12), 16–19.

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