Hot weather, extreme humidity, alcohol, and certain medicines can increase fluid losses, leading to potential dehydration. If you don’t drink enough water throughout the day, you may become thirsty at night.
Certain health conditions and their complications can also make you excessively thirsty.
Dehydration occurs when you lose more fluids than you consume. This can happen if you are sweating, exercising outdoors on a hot day, and not drinking enough water.
Sweating leads to water loss from both your bloodstream and cells, reducing blood volume and causing cells to shrink. This effect is increased if you haven’t had enough water to drink.
Common signs of dehydration include thirst, dark yellow urine, less frequent urination, and fatigue. These cues can be easy to miss during busy days, which might explain why you feel unexpectedly thirsty at night.
Weather extremes, whether cold or hot, can affect your thirst. Cold, dry air draws moisture from your skin and lungs, causing some fluid losses. Hot, dry weather can trap heat within your body, which can also lead to dehydration. You may not notice fluid losses in the heat, as sweat evaporates quickly in hot, dry conditions.
In hot, humid weather, sweat doesn’t evaporate well, so your body sweats more to try to cool down. This additional sweating can lead to more fluid loss.
There is also evidence that airplane cabin pressure from long flights may promote fluid shifts, which can make you feel dehydrated. Even small increases in blood concentration (as little as 1%) can trigger thirst. The reduction in breathable oxygen in the air can also be to blame. Other minor factors may include airflow patterns and the dryness of recycled cabin air.
Certain medications can make you thirsty. For example, antipsychotic drugs such as Zyprexa (olanzapine) can make a person extremely thirsty. This is likely due to the drug’s various side effects, such as frequent urination and dry mouth. This drug may also make it harder for the body to cool down on hot days, which can trap body heat and further trigger your thirst.
Diuretics (water pills) are known to increase urine output by promoting the release of sodium and water. This disrupts the body’s fluid and electrolyte balance, which can lead to dehydration and increased thirst as the body tries to compensate for lost fluids.
Alcohol is drying and has dehydrating effects. When you drink a lot of alcohol, it elevates your sensations of dry mouth and thirst. Heavy drinking influences fluid loss through peeing, which can also make you thirstier. However, consuming very high amounts of alcohol can do the opposite, leading to water retention.
Sleep apnea is characterized by open-mouth breathing. This can make your mouth dry and lead to moisture (water) losses, which can make you dehydrated. Dry mouth alone might make you feel thirsty. If you don’t drink much water during the day, it may also keep you thirsty at night.
Hormones like estrogen and progesterone help control how your body handles fluids and blood pressure. These hormones fluctuate during menstruation (your period) and menopause (after your period ends permanently). When that happens, it can affect your blood circulation and your body’s fluid status.
During menstruation, your body also loses blood, which can contribute to fluid level shifts. This may increase your thirst.
Diabetic ketoacidosis (DKA) is a serious complication that can happen to people with diabetes, especially those with type 1 diabetes. It happens when blood sugar levels get very high and the body’s electrolyte balance is off.
Another serious condition is called hyperosmolar hyperglycemic syndrome (HHS). This mostly affects people with type 2 diabetes.
Both DKA and HHS can be life-threatening and have some of the same warning signs, such as:
- Feeling extremely thirsty
- Very high blood sugar levels
- A dry mouth
- Peeing excessively
- A racing heartbeat (heart palpitations)
Hemoglobin is a protein in red blood cells responsible for transporting oxygen throughout the body. In iron-deficiency anemia, reduced red blood cell counts and hemoglobin levels lower oxygen levels, making you feel tired.
The body may respond to low oxygen levels by increasing heart rate and circulation. In more severe cases of anemia, extreme thirst can be a symptom.
Sjögren’s syndrome is an autoimmune disorder that affects the body’s moisture-producing glands. Inflammation and dysfunction of the lacrimal (tear) and salivary glands often lead to dry eyes and dry mouth.
This decrease in fluid production may cause persistent thirst and discomfort. Staying hydrated and drinking water frequently can help relieve the symptoms of dry mouth.
There are a few ways to reduce your chance of feeling thirsty at night:
- Follow a balanced diet that maintains sodium intake within recommended levels. Avoid eating too much salty food at night, as it can make you thirstier.
- Stay well-hydrated by drinking fluids consistently throughout the day,
- Limit caffeine and alcohol, especially in the evening, as these are diuretic substances that can make you pee more, leading to increased thirst.
- Manage medical conditions like diabetes or Sjögren’s syndrome that can contribute to excessive thirst.
- Consult your healthcare provider about medications that may cause dry mouth or dehydration, and explore alternative treatments if necessary.
- Stay indoors in extreme weather as much as possible. Drink more water if you’ve been outdoors for long periods on very hot or very cold days.
- Regulate indoor temperature and humidity to prevent excessive fluid loss from heat or overly dry air conditioning. If you are on a plane, drink plenty of water to compensate for potential fluid losses due to cabin air conditions.
It is normal to feel thirsty when you’re dehydrated. However, excessive and persistent thirst—a condition known as polydipsia—can reveal an underlying medical issue. Polydipsia is associated with conditions such as DKA, sickle cell anemia, schizophrenia, and significant blood loss.
A hallmark sign of polydipsia is peeing frequently and having urine that is light or almost clear in color. This is known as polyuria (urine output higher than 40–50 mL/kg over a 24-hour period). When a person consumes large amounts of water, it puts pressure on the kidneys to remove excess fluids, with a maximum capacity of about 12 liters per day.
If water intake surpasses the kidneys’ ability to excrete it, this can lead to hyponatremia, a potentially dangerous drop in blood sodium levels. As a result, excessive thirst can cause symptoms such as blurred vision, dizziness, confusion, and potentially seizures.
If you are thirsty, peeing excessively, and experiencing any of these symptoms, it’s essential to get immediate medical attention.
You may feel thirsty at night due to dehydration, an imbalance of body fluids that can occur from excessive sweating or environmental factors like hot or humid weather. Alcohol, certain medications, hormonal changes, and some health conditions can also contribute to thirst.
To manage your thirst, try limiting your salt intake, drinking enough water throughout the day, and regulating your bedroom temperature. If you are still thirsty at night, talk to your healthcare provider to determine if an underlying condition or medication may be causing your thirst.
