Dry Mouth at Night

Why Do I Get Dry Mouth at Night?

Your salivary glands slow down during sleep, so the mouth loses much of its moisture. Dry mouth at night then builds as other factors join in. Typical examples are mouth breathing, snoring, dry bedroom air and alcohol in the evening. Medicines that reduce saliva add to the effect as well. Often two or three triggers act together.

Why teeth are most exposed overnight

Saliva rinses away food debris and neutralises acids from plaque. It also carries calcium and phosphate, which keep enamel strong. During sleep, however, salivary flow becomes negligible, says a review in the Journal of the American Dental Association. As a result, teeth have the least natural protection while you are in bed.

“In ten healthy volunteers, the average pH inside the mouth was 7.3 by day. It measured 7.0 in normal sleep. With a nose clip forcing mouth breathing at night, the average fell to 6.6. Sleeping with the mouth open lowers oral pH, a proposed factor in erosion and decay.”

Choi JE, Waddell JN, Lyons KM, Kieser JA. Intraoral pH and temperature during sleep with and without mouth breathing. Journal of Oral Rehabilitation, 2016.

Xerostomia

The feeling of a dry mouth; saliva measurements can still come back normal.

Hyposalivation

A measurable fall in the amount of saliva the glands produce.

Intraoral pH

The acidity level inside the mouth; lower numbers mean a more acidic environment for enamel.

CPAP

Continuous positive airway pressure: a bedside machine that keeps the airway open with a steady stream of air.

Is Breathing Through Your Mouth the Main Culprit?

For many people it is. Once the nose feels blocked, the body switches to mouth breathing. Air flowing over the tongue and gums then strips away moisture all night. A cold, hay fever or a deviated septum can narrow the nose. Similarly, sleeping on your back can let the jaw drop open.

Snoring and the morning dry mouth

Snorers often sleep with the lips apart, so many wake with a parched tongue. If your mouth is dry at night only during a cold, blame the blocked nose. Still, regular loud snoring deserves a closer look. Our page on snoring causes and where to start explains the usual triggers.

Signs that point to sleep apnoea

Watch for pauses in breathing, gasping or choking sounds and frequent waking. Daytime exhaustion and headaches on waking may come with them. See your GP first, because a doctor decides whether you need a sleep study.

CPAP and nighttime dry mouth

A CPAP machine keeps the airway open with steady air pressure. That air can dry the mouth, too. Nighttime dry mouth gets worse when air leaks out through open lips. First, tell your sleep clinic. They may raise the humidity, offer a full-face mask or add a chin strap.

Could Evening Medicines Be Drying Your Mouth?

Yes, and timing matters for dry mouth at night. Hundreds of medicines reduce saliva, according to the US National Institute of Dental and Craniofacial Research. Examples include antidepressants, allergy antihistamines, diuretics, some blood pressure drugs and bladder medicines. So a bedtime dose adds to the natural fall in saliva during sleep.

Why it seems to come with age

Dry mouth grows more common with age. Even so, the same institute says ageing itself is not the cause. A systematic review of 29 studies put the overall prevalence at 22%. Rates were higher in studies of older adults. One reason is that many people take more medicines as they age. Our guide to dental health after 60 covers mouth care in later life.

Why Are Teeth More at Risk After Dark?

Dry mouth at night leaves acids and food debris on the teeth for longer. As a result, decay risk rises, especially along the gumline and around old fillings. Low saliva makes bad breath and oral thrush more likely too. For denture wearers, a dry mouth can also make the plate feel loose and sore.

Why brushing before bed matters most

Because saliva protection fades overnight, the last brush of the day counts most. Use a fluoride toothpaste, then spit rather than rinse. After that, avoid eating or sipping anything sugary. Regular scale and polish visits remove the tartar that harbours bacteria.

What we check at your appointment

At a check-up we look for dry, sticky soft tissues and the first chalky spots of decay. Patients at higher risk can benefit from a professional fluoride application, which reinforces weak enamel. Recall visits may then move closer together while the dryness lasts. For lasting morning breath, our guide to bad breath lists other common causes.

How Can You Stop Dry Mouth at Night?

Most relief from dry mouth at night comes from the hour before bed. A cooler bedroom, sensible drinks and a careful last brush do most of the work. Medicines are different, however: only your prescriber should change a dose. The checklist below sums up the practical steps.

1. Keep a glass of water by the bed and sip when you wake.
2. Run a humidifier in the bedroom, particularly while the heating is on.
3. Brush with fluoride toothpaste just before sleep.
4. Choose an alcohol-free mouthwash, because alcohol dries the tissues further.
5. Cut back on evening alcohol and caffeine, and stop smoking if you can.
6. Treat a blocked nose; a pharmacist can suggest suitable options.
7. Take dentures out at night and clean them before storing.
8. Sugar-free gum or xylitol lozenges can help saliva flow before bed.

Evening habits that make it worse

Sugary sweets give quick relief but feed decay-causing bacteria. Acidic, spicy and salty foods can sting dry tissues, so save them for earlier in the day. Finally, never stop a prescribed medicine on your own. Talk to the doctor who prescribed it instead.

When Is a Dry Mouth More Than a Night-Time Problem?

Look beyond the bedroom when dry mouth at night carries on into the day. The same applies when home measures stop working after a few weeks. Diabetes, Sjögren’s syndrome and head and neck radiotherapy can all reduce saliva. However, a doctor, not a dentist, diagnoses these conditions.

Symptoms worth a GP appointment

Some combinations deserve a GP appointment rather than another humidifier. Strong thirst with frequent trips to the toilet is one; gritty, dry eyes are another. Your GP can then run blood tests and refer you to a rheumatologist if needed. Similarly, sore white patches, bleeding or trouble eating need prompt attention.