Water: How much should you drink every day?

Water is essential to good health, yet needs vary by individual. These guidelines can help ensure you drink enough fluids.

How much water should you drink each day? It's a simple question with no easy answers. Studies have produced varying recommendations over the years, but in truth, your water needs depend on many factors, including your health, how active you are and where you live.

Although no single formula fits everyone, knowing more about your body's need for fluids will help you estimate how much water to drink each day.

Health benefits of water

Water is your body's principal chemical component and makes up about 60 percent of your body weight. Every system in your body depends on water. For example, water flushes toxins out of vital organs, carries nutrients to your cells and provides a moist environment for ear, nose and throat tissues.

Lack of water can lead to dehydration, a condition that occurs when you don't have enough water in your body to carry out normal functions. Even mild dehydration can drain your energy and make you tired.

How much water do you need?

Every day you lose water through your breath, perspiration, urine and bowel movements. For your body to function properly, you must replenish its water supply by consuming beverages and foods that contain water.

So how much fluid does the average, healthy adult living in a temperate climate need? The Institute of Medicine determined that an adequate intake (AI) for men is roughly 3 liters (about 13 cups) of total beverages a day. The AI for women is 2.2 liters (about 9 cups) of total beverages a day.

What about the advice to drink eight glasses a day?

Everyone has heard the advice, "Drink eight 8-ounce glasses of water a day." That's about 1.9 liters, which isn't that different from the Institute of Medicine recommendations. Although the "8 by 8" rule isn't supported by hard evidence, it remains popular because it's easy to remember. Just keep in mind that the rule should be reframed as: "Drink at least eight 8-ounce glasses of fluid a day," because all fluids count toward the daily total.

Factors that influence water needs

You may need to modify your total fluid intake depending on how active you are, the climate you live in, your health status, and if you're pregnant or breast-feeding.

• Exercise. If you exercise or engage in any activity that makes you sweat, you need to drink extra water to compensate for the fluid loss. An extra 400 to 600 milliliters (about 1.5 to 2.5 cups) of water should suffice for short bouts of exercise, but intense exercise lasting more than an hour (for example, running a marathon) requires more fluid intake. How much additional fluid you need depends on how much you sweat during exercise, and the duration and type of exercise. During long bouts of intense exercise, it's best to use a sports drink that contains sodium, as this will help replace sodium lost in sweat and reduce the chances of developing hyponatremia, which can be life-threatening. Also, continue to replace fluids after you're finished exercising.
• Environment. Hot or humid weather can make you sweat and requires additional intake of fluid. Heated indoor air also can cause your skin to lose moisture during wintertime. Further, altitudes greater than 8,200 feet (2,500 meters) may trigger increased urination and more rapid breathing, which use up more of your fluid reserves.
• Illnesses or health conditions. When you have fever, vomiting or diarrhea, your body loses additional fluids. In these cases, you should drink more water. In some cases, your doctor may recommend oral rehydration solutions, such as Gatorade, Powerade or CeraLyte. Also, you may need increased fluid intake if you develop certain conditions, including bladder infections or urinary tract stones. On the other hand, some conditions such as heart failure and some types of kidney, liver and adrenal diseases may impair excretion of water and even require that you limit your fluid intake.
• Pregnancy or breast-feeding. Women who are expecting or breast-feeding need additional fluids to stay hydrated. Large amounts of fluid are used especially when nursing. The Institute of Medicine recommends that pregnant women drink 2.3 liters (about 10 cups) of fluids daily and women who breast-feed consume 3.1 liters (about 13 cups) of fluids a day.

Beyond the tap: Other sources of water

Although it's a great idea to keep water within reach at all times, you don't need to rely only on what you drink to meet your fluid needs. What you eat also provides a significant portion of your fluid needs. On average, food provides about 20 percent of total water intake. For example, many fruits and vegetables, such as watermelon and tomatoes, are 90 percent or more water by weight.

In addition, beverages such as milk and juice are composed mostly of water. Even beer, wine and caffeinated beverages — such as coffee, tea or soda — can contribute, but these should not be a major portion of your daily total fluid intake. Water is still your best bet because it's calorie-free, inexpensive and readily available.

Staying safely hydrated

Generally if you drink enough fluid so that you rarely feel thirsty and produce 1.5 liters (6.3 cups) or more of colorless or light yellow urine a day, your fluid intake is probably adequate. If you're concerned about your fluid intake or have health issues, check with your doctor or a registered dietitian. He or she can help you determine the amount of water that's right for you.

To ward off dehydration and make sure your body has the fluids it needs, make water your beverage of choice. It's also a good idea to:

• Drink a glass of water or other calorie-free or low-calorie beverage with each meal and between each meal.
• Drink water before, during and after exercise.

Although uncommon, it is possible to drink too much water. When your kidneys are unable to excrete the excess water, the electrolyte (mineral) content of the blood is diluted, resulting in low sodium levels in the blood, a condition called hyponatremia. Endurance athletes, such as marathon runners, who drink large amounts of water, are at higher risk of hyponatremia. In general, though, drinking too much water is rare in healthy adults who eat an average Indian diet.

A person who is 110 pounds
and is exercising for 30 minutes ,
is not pregnant,
is not breastfeeding,
does not live at a high altitude,
does not live in a dry climate,
drinks 0 alcoholic drink(s),
when the weather is not very hot or very cold,
and is not sick with fever or diarrhea should have:

58 ounces of water today, or 1.7 liters.

If you eat a healthy diet, about 20 percent of your water may come from the foods you eat. If you eat a healthy diet you can drink 46.4 ounces of water today, or 1.4 liters.

Water is an obvious source for your daily fluid needs. Other good beverages include milk, herbal teas, low-sodium broth, 100% fruit and vegetable juices. Soft drinks will also count toward your daily total of fluid, just remember that sugar sweetened soft drinks and fruit juices add extra calories to you daily diet that you don't need, while drinking water may help you lose weight.

Help People

“If you want others to be happy, practice compassion. If you want to be happy, practice compassion.” - Dalai Lama

Too often the trend in our society is for people to be separated from either other, to be cut off from the great mass of humanity, and in doing so to be dehumanized a little bit more with each step.

Cars have taken us off the streets, where we used to greet each other and stop to chat. Cubicles have taken away a bit of the humanity in working, as have factories and even computers to some extent. Television has planted us firmly in our living rooms, instead of out with other people. Even movie theaters, where many people get together, cut us off from true conversation because we’re staring at a big screen.

And while I’m not railing against any of these inventions (except perhaps the cubicle), what we must guard against is the tendency of that individuality to have us focused on ourselves to the exclusion of our fellow human beings. The tendency towards selfishness rather than giving, on helping ourselves rather than helping our brothers and sisters in humanity.

I’m not saying we’re all like that, but it can happen, if we’re not careful.

So strike back against the selfishness and greed of our modern world, and help out a fellow human being today. Not next month, but today.

Helping a fellow human being, while it can be inconvenient, has a few humble advantages:

1. It makes you feel better about yourself;
2. It connects you with another person, at least for a moment, if not for life;
3. It improves the life of another, at least a little;
4. It makes the world a better place, one little step at a time;
5. And if that kindness is passed on, it can multiply, and multipy.

So take just a few minutes today, and do a kindness for another person. It can be something small, or the start of something big. Ask them to pay it forward. Put a smile on someone’s face.

Don’t know where to start? Here’s an extremely incomplete list, just to get you thinking — I’m sure you can come up with thousands more if you think about it.

1. Smile and be friendly. Sometimes a simple little thing like this can put a smile and warm feeling in someone else’s heart, and make their day a little better. They might then do the same for others.
2. Call a charity to volunteer. You don’t have to go to a soup kitchen today. Just look up the number, make the call, and make an appointment to volunteer sometime in the next month. It can be whatever charity you like. Volunteering is one of the most amazing things you can do.
3. Donate something you don’t use. Or a whole box of somethings. Drop them off at a charity — others can put your clutter to good use.
4. Make a donation. There are lots of ways to donate to charities online, or in your local community. Instead of buying yourself a new gadget or outfit, spend that money in a more positive way.
5. Redirect gifts. Instead of having people give you birthday or Christmas gifts, ask them to donate gifts or money to a certain charity.
6. Stop to help. The next time you see someone pulled over with a flat tire, or somehow in need of help, stop and ask how you can help. Sometimes all they need is a push, or the use of your cell phone.
7. Teach. Take the time to teach someone a skill you know. This could be teaching your grandma to use email, teaching your child to ride a bike, teaching your co-worker a valuable computer skill, teaching your spouse how to clean the darn toilet. OK, that last one doesn’t count.
8. Comfort someone in grief. Often a hug, a helpful hand, a kind word, a listening ear, will go a long way when someone has lost a loved one or suffered some similar loss or tragedy.
9. Help them take action. If someone in grief seems to be lost and doesn’t know what to do, help them do something. It could be making funeral arrangements, it could be making a doctor’s appointment, it could be making phone calls. Don’t do it all yourself — let them take action too, because it helps in the healing process.
10. Buy food for a homeless person. Cash is often a bad idea if it’s going to be used for drugs, but buying a sandwich and chips or something like that is a good gesture. Be respectful and friendly.
11. Lend your ear. Often someone who is sad, depressed, angry, or frustrated just needs someone who will listen. Venting and talking through an issue is a huge help.
12. Help someone on the edge. If someone is suicidal, urge them to get help. If they don’t, call a suicide hotline or doctor yourself to get advice.
13. Help someone get active. A person in your life who wants to get healthy might need a helping hand — offer to go walking or running together, to join a gym together. Once they get started, it can have profound effects.
14. Do a chore. Something small or big, like cleaning up or washing a car or doing the dishes or cutting a lawn.
15. Give a massage. Only when appropriate of course. But a massage can go a long way to making someone feel better.
16. Send a nice email. Just a quick note telling someone how much you appreciate them, or how proud you are of them, or just saying thank you for something they did.
17. Show appreciation, publicly. Praising someone on a blog, in front of coworkers, in front of family, or in some other public way, is a great way to make them feel better about themselves.
18. Donate food. Clean out your cupboard of canned goods, or buy a couple bags of groceries, and donate them to a homeless shelter.
19. Just be there. When someone you know is in need, sometimes it’s just good to be there. Sit with them. Talk. Help out if you can.
20. Be patient. Sometimes people can have difficulty understanding things, or learning to do something right. Learn to be patient with them.
21. Tutor a child. This might be difficult to do today, but often parents can’t afford to hire a tutor for their child in need of help. Call a school and volunteer your tutoring services.
22. Create a care package. Soup, reading material, tea, chocolate … anything you think the person might need or enjoy. Good for someone who is sick or otherwise in need of a pick-me-up.
23. Lend your voice. Often the powerless, the homeless, the neglected in our world need someone to speak up for them. You don’t have to take on that cause by yourself, but join others in signing a petition, speaking up a a council meeting, writing letters, and otherwise making a need heard.
24. Offer to babysit. Sometimes parents need a break. If a friend or other loved one in your life doesn’t get that chance very often, call them and offer to babysit sometime. Set up an appointment. It can make a big difference.
25. Love. Simply finding ways to express your love to others, whether it be your partner, child, other family member, friend, co-worker, or a complete stranger … just express your love. A hug, a kind word, spending time, showing little kindnesses, being friendly … it all matters more than you know.

How far that little candle throws his beams!
So shines a good deed in a weary world.
- William Shakespeare

Sleep

Sleep is a naturally recurring state characterized by reduced or absentconsciousness, relatively suspended sensory activity, and inactivity of nearly allvoluntary muscles.  It is distinguished from quiet wakefulness by a decreased ability to react to stimuli, and is more easily reversible than being in hibernation or acoma. Sleep is a heightened anabolic state, accentuating the growth and rejuvenation of the immune, nervous, skeletal and muscular systems. It is observed in all mammals, all birds, and many reptiles, amphibians, and fish.

The purposes and mechanisms of sleep are only partially clear and are the subject of intense research. Sleep is often thought to help conserve energy,  but actually decreases metabolism only about 5–10%.  Hibernating animals need to sleep despite the hypometabolism seen in hibernation, and in fact they must return from hypothermia to euthermia in order to sleep, making sleeping "energetically expensive."

Optimal amount in humans

Adult

The optimal amount of sleep is not a meaningful concept unless the timing of that sleep is seen in relation to an individual's circadian rhythms. A person's major sleep episode is relatively inefficient and inadequate when it occurs at the "wrong" time of day; one should be asleep at least six hours before the lowest body temperature. The timing is correct when the following two circadian markers occur after the middle of the sleep episode and before awakening:

• maximum concentration of the hormone melatonin, and
• minimum core body temperature.

For more information on the human circadian rhythm and body temperature, see Biological markers (in the article Circadian rhythm).

Human sleep needs can vary by age and among individuals, and sleep is considered to be adequate when there is no daytime sleepiness or dysfunction. Moreover, self-reported sleep duration is only moderately correlated with actual sleep time as measured by actigraphy, and those affected with sleep state misperception may typically report having slept only four hours despite having slept a full eight hours.

A University of California, San Diego psychiatry study of more than one million adults found that people who live the longest self-report sleeping for six to seven hours each night. Another study of sleep duration and mortality risk in women showed similar results. Other studies show that "sleeping more than 7 to 8 hours per day has been consistently associated with increased mortality," though this study suggests the cause is probably other factors such as depression and socioeconomic status, which would correlate statistically. It has been suggested that the correlation between lower sleep hours and reduced morbidity only occurs with those who wake naturally, rather than those who use an alarm.

Main health effects of sleep deprivation,^[27] indicating impairment of normal maintenance by sleep

Researchers at the University of Warwick and University College London have found that lack of sleep can more than double the risk of death from cardiovascular disease, but that too much sleep can also be associated with a doubling of the risk of death, though not primarily from cardiovascular disease. Professor Francesco Cappuccio said, "Short sleep has been shown to be a risk factor for weight gain, hypertension, and Type 2 diabetes, sometimes leading to mortality; but in contrast to the short sleep-mortality association, it appears that no potential mechanisms by which long sleep could be associated with increased mortality have yet been investigated. Some candidate causes for this include depression, low socioeconomic status, and cancer-related fatigue... In terms of prevention, our findings indicate that consistently sleeping around seven hours per night is optimal for health, and a sustained reduction may predispose to ill health."

Furthermore, sleep difficulties are closely associated with psychiatric disorders such as depression, alcoholism, and bipolar disorder. Up to 90% of adults with depression are found to have sleep difficulties. Dysregulation found on EEG includes disturbances in sleep continuity, decreased delta sleep and altered REM patterns with regard to latency, distribution across the night and density of eye movements.

Hours by age

Children need more sleep per day in order to develop and function properly: up to 18 hours for newborn babies, with a declining rate as a child ages.  A newborn baby spends almost 9 hours a day in REM sleep. By the age of five or so, only slightly over two hours is spent in REM. Studies say that school age children need about 10 to 11 hours of sleep.

Age and condition	Average amount of sleep per day
Newborn	up to 18 hours
1–12 months	14–18 hours
1–3 years	12–15 hours
3–5 years	11–13 hours
5–12 years	9–11 hours
Adolescents	9–10 hours
Adults, including elderly	7–8 hours
Pregnant women	8(+) hours

Sleep stages

In mammals and birds, sleep is divided into two broad types: rapid eye movement (REM) and non-rapid eye movement (NREM or non-REM) sleep. Each type has a distinct set of associated physiological, neurological, and psychological features. The American Academy of Sleep Medicine (AASM) further divides NREM into three stages: N1, N2, and N3, the last of which is also called delta sleep or slow-wave sleep(SWS).

Hypnogram showing sleep cycles from midnight to 6.30 am, with deep sleep early on. There is more REM (marked red) before waking.

Stage N3 sleep; EEG highlighted by red box. Thirty seconds of deep sleep, here with greater than 50% delta waves.

REM sleep; EEG highlighted by red box; eye movements highlighted by red line. Thirty seconds of sleep.

Sleep proceeds in cycles of REM and NREM, the order normally being N1 → N2 → N3 → N2 → REM. There is a greater amount of deep sleep (stage N3) earlier in the sleep cycle, while the proportion of REM sleep increases later in the sleep cycle and just before natural awakening.

The stages of sleep were first described in 1937 by Alfred Lee Loomis and his coworkers, who separated the different electroencephalography (EEG) features of sleep into five levels (A to E), which represented the spectrum from wakefulness to deep sleep.  In 1953, REM sleep was discovered as distinct, and thusWilliam Dement and Nathaniel Kleitman reclassified sleep into four NREM stages and REM. The staging criteria were standardized in 1968 by Allan Rechtschaffen and Anthony Kales in the "R&K sleep scoring manual." In the R&K standard, NREM sleep was divided into four stages, with slow-wave sleep comprising stages 3 and 4. In stage 3, delta waves made up less than 50% of the total wave patterns, while they made up more than 50% in stage 4. Furthermore, REM sleep was sometimes referred to as stage 5.

In 2004, the AASM commissioned the AASM Visual Scoring Task Force to review the R&K scoring system. The review resulted in several changes, the most significant being the combination of stages 3 and 4 into Stage N3. 

Sleep stages and other characteristics of sleep are commonly assessed by polysomnography in a specialized sleep laboratory. Measurements taken include EEG of brain waves,electrooculography (EOG) of eye movements, and electromyography (EMG) of skeletal muscleactivity. In humans, each sleep cycle lasts from 90 to 110 minutes on average, and each stage may have a distinct physiological function. This can result in sleep that exhibits loss of consciousness but does not fulfill its physiological functions (i.e., one may still feel tired after apparently sufficient sleep).

Scientific studies on sleep have shown that sleep stage at awakening is an important factor in amplifying sleep inertia. Alarm clocks involving sleep stage monitoring appeared on the market in 2005. Using sensing technologies such as EEG electrodes or accelerometers, these alarm clocks are supposed to wake people only from light sleep.

[edit]NREM sleep

According to the 2007 AASM standards, NREM consists of three stages. There is relatively little dreaming in NREM.

Stage N1 refers to the transition of the brain from alpha waves having a frequency of 8–13 Hz(common in the awake state) to theta waves having a frequency of 4–7 Hz. This stage is sometimes referred to as somnolence or drowsy sleep. Sudden twitches and hypnic jerks, also known as positive myoclonus, may be associated with the onset of sleep during N1. Some people may also experience hypnagogic hallucinations during this stage. During N1, the subject loses some muscle tone and most conscious awareness of the external environment.

Stage N2 is characterized by sleep spindles ranging from 11 to 16 Hz (most commonly 12–14 Hz) and K-complexes. During this stage, muscular activity as measured by EMG decreases, and conscious awareness of the external environment disappears. This stage occupies 45–55% of total sleep in adults.

Stage N3 (deep or slow-wave sleep) is characterized by the presence of a minimum of 20% delta waves ranging from 0.5–2 Hz and having a peak-to-peak amplitude >75 μV. (EEG standards define delta waves to be from 0 to 4 Hz, but sleep standards in both the original R&K, as well as the new 2007 AASM guidelines have a range of 0.5–2 Hz.) This is the stage in which parasomnias such as night terrors, nocturnal enuresis, sleepwalking, and somniloquy occur. Many illustrations and descriptions still show a stage N3 with 20–50% delta waves and a stage N4 with greater than 50% delta waves; these have been combined as stage N3.

REM sleep

Rapid eye movement sleep, or REM sleep, accounts for 20–25% of total sleep time in most human adults. The criteria for REM sleep include rapid eye movements as well as a rapid low-voltage EEG. Most memorable dreaming occurs in this stage. At least in mammals, a descending muscular atonia is seen. Such paralysis may be necessary to protect organisms from self-damage through physically acting out scenes from the often-vivid dreams that occur during this stage.

[edit]Timing

The human biological clock

Sleep timing is controlled by the circadian clock, sleep-wake homeostasis, and in humans, within certain bounds, willed behavior. The circadian clock—an inner timekeeping, temperature-fluctuating, enzyme-controlling device—works in tandem with adenosine, a neurotransmitter that inhibits many of the bodily processes associated with wakefulness. Adenosine is created over the course of the day; high levels of adenosine lead to sleepiness. In diurnal animals, sleepiness occurs as the circadian element causes the release of the hormone melatonin and a gradual decrease in core body temperature. The timing is affected by one'schronotype. It is the circadian rhythm that determines the ideal timing of a correctly structured and restorative sleep episode.

Homeostatic sleep propensity (the need for sleep as a function of the amount of time elapsed since the last adequate sleep episode) must be balanced against the circadian element for satisfactory sleep. Along with corresponding messages from the circadian clock, this tells the body it needs to sleep.  Sleep offset (awakening) is primarily determined by circadian rhythm. A person who regularly awakens at an early hour will generally not be able to sleep much later than his or her normal waking time, even if moderately sleep-deprived.

Sleep duration is affected by the gene DEC2. Some people have a mutation of this gene; they sleep two hours less than normal. Neurology professor Ying-Hui Fu and her colleagues bred mice that carried the DEC2 mutation and slept less than normal mice.

Insomnia

Insomnia is a general term describing difficulty falling asleep and staying asleep. Insomnia can have many different causes, including psychological stress, a poor sleep environment, an inconsistent sleep schedule, or excessive mental or physical stimulation in the hours before bedtime. Insomnia is often treated through behavioral changes like keeping a regular sleep schedule, avoiding stimulating or stressful activities before bedtime, and cutting down on stimulants such as caffeine. Patients are often counseled to improve their sleep environment by installing heavy drapes to shut out all sunlight, and keeping computers, televisions and work materials out of the sleeping area.

A 2010 review of published scientific research suggested that exercise generally improves sleep for most people, and helps sleep disorders such as insomnia. The optimum time to exercise may be 4 to 8 hours before bedtime, though exercise at any time of day is beneficial, with the exception of heavy exercise taken shortly before bedtime, which may disturb sleep. However there is insufficient evidence to draw detailed conclusions about the relationship between exercise and sleep.

Sleeping medications such as Ambien and Lunesta are an increasingly popular treatment for insomnia, and have become a major source of revenue for drug companies. Although these nonbenzodiazepene medications are generally believed to be better and safer than earlier generations of sedatives, they have still generated some controversy and discussion regarding side-effects.

White noise appears to be a promising treatment for insomnia.