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Blog Have you ever been faced with a sudden feeling of thirst when you lie down in bed after a busy day? On the one hand, the feeling of thirst that dries your palate, on the other hand, the worry that “if I drink water now, I will have to go to the toilet at night and my sleep will be disturbed”. At this point, the critical question comes to mind: Is it healthy to drink water at night? The answers to this question are usually not as simple as “yes” or “no”; because behind the answer lies complex physiological processes such as our body’s biological clock, kidney functions and sleep cycles.
As health-conscious individuals, we know that water is our source of life. However, the timing of water consumption is as important as the amount. It can be difficult to find the truth between the myths circulating on the internet such as “drinking water at night prevents heart attack” and fear scenarios such as “drinking water at night causes oedema”. In this guide, we will examine the real effects of drinking water at night on your body in the light of scientific data and expert opinions. Our aim is to show you how you can optimise your hydration (fluid balance) without disturbing your circadian rhythm.
If you suffer from frequent night wakings or want to benefit from the power of water in the process of weight control, this article is for you.
Physiological Effects of Drinking Water at Night on the Body
The human body has different working principles day and night. Metabolism and excretory systems, which are active during the day, switch to “rest and repair” mode at night. To understand the effects of drinking water at night, we must first look at how the body manages this transition.
Circadian Rhythm and Renal Function
The circadian rhythm, our body’s 24-hour biological clock, governs not only the sleep-wake cycle, but also the release of hormones and the speed at which organs function. At night, the body increases the production of Antidiuretic Hormone (ADH) or vasopressin. This hormone instructs the kidneys to “retain water and slow down urine production”.
Under normal conditions, thanks to this mechanism, the amount of urine produced during the night decreases but its density increases. In this way, we can complete our 6-8 hours of sleep without the need to go to the toilet. However, if you consume large amounts of fluids just before going to bed, which is incompatible with your circadian rhythm, you overcome the suppressive effect of ADH and force your kidneys to work overtime. This is an interference with the natural flow of your biological clock.
What is nocturia (night urination)?
The most common consequence of drinking too much water just before going to bed at night is the medical name Nocturia. Nocturia is a condition in which an individual wakes up from sleep to urinate one or more times during the night. According to Sleep Foundation data, one in three adults over the age of 30 (33%) suffer from nocturia.
Nocturia is not just “going to the toilet”; it is also the biggest enemy of quality sleep. When water consumption at night is uncontrolled, the bladder capacity is filled and a “wake up” signal is sent to the brain. This can turn into a chronic sleep disorder, especially when combined with factors such as decreased ADH production with age or prostate enlargement.
Harm and Risks of Drinking Water Before Going to Bed at Night
Although drinking water is vital, it can do more harm than good when the timing is wrong. Especially its effects on sleep quality should not be ignored.
Sleep Quality and Splitting of the REM Cycle
Sleep consists of phases called light sleep, deep sleep and REM (Rapid Eye Movement) sleep. The most important phases in which the body is physically and mentally renewed are deep sleep and REM phases. According to research published in ScienceDirect, 53% of sleep interruptions in adults are caused by going to the toilet at night.
When you wake up at night to urinate, your sleep cycle is interrupted. Even if you fall asleep again, the cycle can go back to the beginning and you may be deprived of restorative REM sleep. The long-term effects of this condition are:
- Morning fatigue and trouble focusing.
- Weakening of the immune system.
- Increased stress hormones (cortisol).
- Slowing of the metabolic rate.
Does drinking water at night cause oedema?
Another frequently asked question is whether drinking water at night causes swelling of the face and eyes (oedema) in the morning. In fact, water itself does not directly cause oedema in individuals with healthy kidneys. On the contrary, dehydration (thirst) can trigger oedema by causing the body to retain existing water.
However, consuming sodium (salt) containing snacks with water late at night or having severe kidney failure problems can cause you to wake up swollen in the morning. For a healthy individual, a reasonable amount of water drunk at night is filtered by the kidneys. What is important to prevent oedema formation is the quality and sodium balance of the water you drink. Using a water purifier to ensure the quality of the water you use in your home can help you optimise the sodium and mineral balance of the water entering your body.
Benefits of Drinking Water at Night: When and How to Drink?
We have mentioned the risks, but this does not mean that drinking water at night is completely forbidden. With the right timing and amount, drinking water at night can turn into a “detox” opportunity for your body.
Body Temperature Regulation and Detox Effect
Body temperature naturally drops during sleep. However, some individuals are categorised as “hot sleepers” and may experience night sweats. Drinking a small amount of water before going to bed can help regulate body temperature and facilitate the transition to a cooler and more comfortable sleep.
In addition, during the night the body performs cellular repair and cleansing. Water is essential for the transport of these metabolic wastes (toxins) and their elimination in the morning. Ancient teachings, such as Traditional Chinese Medicine, also believe that warm water drunk at night before going to bed eases digestion and balances the flow of energy in the body.
Hydration for Morning Fitness
Even if we do not move at all during sleep, we lose a significant amount of water through breathing and skin. Studies show that an average of 300-500 ml of water is lost during an 8-hour sleep. This is the main reason for waking up in the morning “dehydrated” and with a headache.
A glass of water drunk before going to bed can help to compensate for this loss in advance. However, the critical point is to replace this lost water as soon as you wake up in the morning. For more detailed information on the subject, you can take a look at our article Is it useful to drink water on an empty stomach? Water drunk in the morning accelerates metabolism by 24%, allowing you to start the day energetically.
Does Drinking Water at Night Lose Weight?
Water consumption is a critical tool for those who are in the process of losing weight. So, does drinking water at night directly weaken?
Thermogenic Effect of Cold Water and Calorie Burn
According to a study published in the Journal of Clinical Endocrinology & Metabolism, drinking cold water can temporarily increase metabolic rate by 24-30%. This is called the “thermogenic effect”; the body expends extra energy to bring the cold water to body temperature.
This effect also applies to cold water drunk before going to bed at night. However, this alone is not a miraculous weight loss method. It only makes a small contribution to the overall calorie burn.
Hunger Signals and Night Eating Syndrome
The biggest impact of drinking water at night on weight control is its role in combating Night Eating Syndrome. Often the brain confuses thirst signals with hunger signals. The desire for a late-night “snack” may actually be the body’s call for water.
Drinking a glass of water before going to bed can suppress Ghrelin (hunger hormone) levels by filling the stomach and prevent unnecessary calorie intake.
Ideal Timing: When Should You Stop Drinking Water?
The golden key to reaping the benefits and avoiding the harms of drinking water at night: Timing.
“2 Hour Rule” Recommended by Experts
Urologists and sleep experts agree on the “2-hour rule”. According to this rule, you should drastically cut your fluid intake (water, tea, coffee) exactly 2 hours before your bedtime.
For example, if you go to sleep at 23:00, you should have drunk your last large glass by 21:00. This is enough time for the kidneys to filter the fluid and for the bladder to empty completely before sleep. What to do if you feel thirsty between 21:00 and 23:00? You should only take small sips, just enough to wet your mouth.
Warm Water or Cold Water?
| Water Type | Impact | When Should It Be Preferred? |
| Cold Water | Accelerates metabolism (thermogenic effect), can give a feeling of alertness. | During the day or early evening for those aiming for weight control. |
| Warm Water | Relaxes digestion, soothes the nervous system, facilitates the transition to sleep. | Ideal for drinking in small sips just before bedtime. |
Drinking warm water will relax your body, especially if you have a sensitive stomach or have difficulty falling asleep. The quality of drinking water is just as important as the temperature; chlorinated water or water containing heavy metals can upset the stomach.
Myths and Facts
Some information spread among the public can cause confusion. Here is a comparison of the most common myths with scientific facts:
| Myth (False Information) | Scientific Fact |
| Myth: “Drinking water before going to bed will definitely prevent a heart attack.” | Reality: Hydration is important for general heart health and keeps the blood flowing. However, no direct “shielding” effect of a glass of water drunk just before going to bed has been proven to prevent a heart attack at that moment. This is a viral internet myth. (Source: American Heart Association) |
| Myth: “Drinking water at night makes the face swell.” | Reality: Healthy kidneys filter excess water. Facial swelling is usually caused by excessive salt consumption or hormonal imbalances, not just from water. |
| Myth: “Drinking water makes you sleepy.” | It’s true: Only the need for a toilet interrupts sleep. The chemical composition of water does not cause sleep disturbance; on the contrary, dehydration can cause insomnia. |
Who Should Pay Attention When Drinking Water at Night?
Some health conditions require extra sensitivity to fluid intake at night.
Warnings for Heart, Diabetes and Kidney Patients
- Heart Failure: In patients with heart failure, the body may not be able to remove fluid, which may cause oedema in the lungs or legs. Fluid intake of these patients is usually restricted under the supervision of a doctor.
- Kidney Diseases: If the filtering capacity of the kidneys is low, excess fluid taken at night accumulates in the body and can trigger hypertension.
- Diabetes People with diabetes already tend to urinate frequently (polyuria). Drinking too much water at night worsens this condition and significantly reduces sleep quality.
If you are in these groups, you should stick to the “daily fluid limit” set by your doctor and minimise fluid intake in the evening.
People with Dry Mouth (Xerostomia)
People who sleep with their mouth open or who take certain medications may experience dry mouth (Xerostomia). For these people, it is essential to keep a glass of water by the bedside. However, the strategy should not be “guzzling”, but only “sipping” enough to moisten the inside of the mouth. In this way, the feeling of dryness can be relieved without triggering the need for a toilet.
Summary: What is the Ideal Water Drinking Routine?
The ideal water drinking schedule for a healthy life, quality sleep and kidney health should be as follows:
- Morning (07:00 – 09:00): Drink 1-2 glasses of water as soon as you wake up. Make up for the loss during the night.
- During the day (09:00 – 18:00): Drink water at regular intervals without waiting for thirst. Although the answer to the question of how many litres of water you should drink per day depends on your weight, hydration throughout the day is essential. Using an easy-to-access water purification dispenser at work or at home will help you remember to drink water.
- Evening (18:00 – 20:00): Slow down water consumption.
- 2 hours before bedtime: Stop fluid intake.
- Bedtime: Only take a small sip if you are very thirsty or need to take medicine.
In addition, the water consumption of babies, who are the most sensitive individuals at home, requires similar care. It is critical for their development and sleep patterns for parents to be careful about how the water that babies drink should be.
Frequently Asked Questions
Why not drink more water at night?
Drinking too much water just before going to bed at night prevents the kidneys from resting during the night. This leads to nocturia (night-time urination) and interrupts REM sleep. Interrupted sleep can lead to morning tiredness, problems with focus and, in the long term, a weakened immune system.
Is it useful to drink water at night?
It is beneficial depending on the amount and timing. Water drunk at the right time (up to 2 hours before bedtime) regulates body temperature, supports cellular repair (detox) during the night and provides a more energetic wake-up in the morning. However, if it is to be drunk just before bedtime, it should only be sipped to relieve dry mouth.
Does drinking water at night make you lose weight?
Drinking water does not burn fat directly, but indirectly helps with weight control. It restricts calorie intake by preventing night hunger (night eating syndrome). In addition, drinking cold water temporarily accelerates metabolism by 24-30% as the body expends energy to heat the water (thermogenic effect).
How much water should you drink at night?
Urologists and sleep specialists recommend that you stop drinking water, tea and coffee 2 hours before bedtime so that the kidneys can filter the fluid and the bladder can empty. For example, if you go to bed at 23:00, you should stop drinking after 21:00.
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