How to Become Smarter (22 page)

In conclusion, research shows that moderate cooling has psychostimulant effects and therefore can increase alertness. You can use this approach to normalize the sleep pattern by reducing sleepiness in the morning and afternoon.

• Moderate cooling of the body shares many biological effects with psychostimulant drugs, including increased blood pressure (a small temporary increase), constriction of blood vessels, slightly increased production of heat, reduced fatigue, increased activity and information processing speed, and elevation of mood.
  
• Similar to psychostimulants, moderate cooling increases alertness and disrupts sleep.
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There are many different ways of cooling the body. I developed a convenient procedure called “adapted cold shower.” You can use this technique to reduce sleepiness when you feel drowsy because of jetlag or all-night studies. (
Endnote T
describes the technical rationale for this cooling procedure.) It has several advantages over coffee but in rare cases can have undesirable effects, as you will see at the end of this chapter. In these cases coffee is more useful than hydrotherapy. The adapted cold shower is effective at improving alertness and information processing speed (the speed of thinking [
924
]). At the same time, this procedure is safe and easy to do, unlike the regular “sudden” cold shower.

You can use the method as follows: start with a tepid shower, 34 to 36°C (93 to 97°F), for one to three minutes. Get out of the shower and set the water temperature to about 20°C (68°F). Then get back in the shower and start gradually and slowly expanding the area of contact with the cold water from the feet up. This gradual adaptation phase should take another 3 to 5 minutes. After that, take the whole-body cold shower for 2 to 5 minutes. If you are feeling tired and sleepy, the adapted cold shower will make you alert and energetic within minutes.
It has other effects as well: elevated internal mood, increased activity, reduced pain,
^U
reduced fatigue, relief of fever [
357
], temporary constriction of blood vessels throughout the body, and a brief increase in blood pressure. Cold showers also reduce nausea and loss of appetite, if these symptoms are present,
^V
but this procedure does not seem to increase normal appetite. Repeated cooling can also stimulate cellular immunity (reviewed in [
393
]). In most cases adapted cold showers increase capacity for work, especially heavy manual work. You may get a strong urge to go for a walk or do some physical exercise after a cold shower. Yet adapted cold showers may reduce motivation for work if your mood is elevated. They can also increase distractibility if you are feeling overactive. The last section of this chapter describes possible adverse effects in more detail.

Avoid
sudden
cold showers because they are difficult to do and can cause confusion and slow you down. They are too shocking for the central nervous system and work like a Taser blast. Sudden cold showers can increase anxiety, based on my experience. Adapted cold showers, on the other hand, do not have these negative effects and are not stressful at all. In one study the brief cooling of the body improved performance of complex mental tasks [
362
]. In my experience this is true of the adapted cold shower.

Moderate cooling is safe for healthy people [
394
-
399
]. Under certain circumstances, however, it is best to avoid it:

• if a cough is present;
  
• at night, because it may disrupt normal sleep patterns;
  
• if mood is elevated, because it can elevate mood further and reduce motivation for work.
  

Coffee can also increase alertness. Thus it may seem that using such a complicated procedure is unnecessary when you can have one or two cups of strong coffee. If caffeine works well for you, continue using it. It is a legal stimulant and there is no reason why you should not use it to improve your mental abilities when necessary. But coffee may not be effective for some people. It isn’t for me. It doesn’t keep me up all night, even at large doses, and I feel awful the next day after a large dose. If my mood is low or apathetic or if I feel bad physically, coffee makes matters worse. This is not the case with cold showers. In my experience coffee has little or no effect on mood and large doses increase nervousness [
400
]. Adapted cold showers, on the other hand, have a strong mood-lifting effect and do not increase, and may reduce, nervousness [
376
].

I had been using adapted cold showers regularly for about three and a half years when I discovered that they can interfere with writing (Chapter Five). I stopped using them so often and now take one if I feel bad physically, feel sleepy at an inappropriate time of day, or am dog-tired. This amounts to one or two a month. On the rare occasions when I have a fever, I use cold showers two or three times a day in combination with acetaminophen (brand name
Tylenol
®). If I have a headache, which can happen several times a year, I use the head shower (discussed in the next section) every two hours in combination with acetaminophen.

For the first one and a half years starting in August 2005, I was able to use cold showers twice a day, in the morning and in the afternoon, without noticeable problems. Later I had to reduce the frequency 2- to 4-fold because of insomnia and symptoms of hypomania. Nowadays if I take adapted cold showers once a day in the morning, I get insomnia. It is possible that the long-term use of cold showers increased my sensitivity to this procedure. If some event has disrupted your sleep pattern and you feel sleepy in the morning, you may consider using adapted cold showers until your sleep pattern normalizes. If you wish, you can combine this approach with a sedative diet. In my personal experience combining cold hydrotherapy in the morning with hot hydrotherapy at night is not effective against insomnia and can cause sleep problems when there are none. In the absence of sleep problems you do not need to use cold showers daily. I take warm showers daily but I do not use either cold or hot showers more than once a week, with rare exceptions.

• Adapted cold showers at 20 degrees Centigrade (68°F) that include a 3- to 5-minute gradual adaptation phase are easy to do and not stressful.
  
• They are effective as a wakefulness-promoting treatment in the morning or afternoon.
  
• Adapted cold showers have several other beneficial effects: they improve mood and reduce fatigue, fever, nausea, and pain.
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Many people believe that a cold shower will make them ill; in particular, it “can cause” a cold or the flu. Although numerous studies of moderate cooling show that it does not cause respiratory illnesses [
394
-
399
], the popular notion about the dangers of cooling persists among the populace. This belief is in part correct in that
severe
cooling, which lowers core body temperature below 35°C (95°F), the state known as hypothermia, can indeed have adverse health effects. This can happen as a result of immersion in ice-cold water or administration of certain drugs. Using special “water blankets,” researchers can achieve mild hypothermia that lasts for several hours or several days. This treatment suppresses the immune system and predisposes the person to bacterial and viral infections. Severe hypothermia (core body temperature below 28°C or 82°F) can cause pulmonary edema (swelling of the lungs) within minutes [
401
-
403
]. In the vast majority of people, cold showers at 20°C (68°F) cannot lower core body temperature below 37°C (98.6°F) and therefore will not have the aforementioned adverse effects [
378
].

Epidemiologists know that upper respiratory tract infections occur predominantly, though not exclusively, during the cold time of the year. The mechanism underlying this phenomenon is unknown [
404
,
405
], although two recent studies provide a possible explanation. The first shows that inhalation of cold air by horses during exercise suppresses immunity in the mucous membrane of the respiratory tract [
406
]. This immunosuppressive effect of cold air can predispose a person to the flu or a cold. The other study shows that cold, dry air improves transmission and survival of influenza virus [
407
]. Cold air contains much less moisture than warm air. Transmission and survival of influenza virus in moist, warm air are much lower. The folk wisdom of keeping a boiling kettle in the house to prevent the spread of influenza among family members should be effective. Therefore, it is possible that the predominant occurrence of flu epidemics during the colder seasons is the result of:

1. immunosuppression resulting from inhaling cold air;
   
2. improved transmission and survival of the influenza virus in cold air.
   

Cold showers in the atmosphere of room-temperature air will not predispose a person to influenza. In contrast, ice-cold food can cause a respiratory illness. Personal experience shows that if I eat cold food and drinks (out of the fridge, 4°C or 39°F) for 2 or 3 days, there is about a 30% chance that I will contract a cold. I have not documented those experiments and I couldn’t find similar studies in scientific literature.

Personal experience suggests that moderately cold showers cannot cause respiratory infections, but if a cough is present, cold showers can sometimes aggravate this symptom. I do not have a good explanation for this observation; cold showers at 20°C (68°F) cannot cause significant cooling of the respiratory tract, so it is unclear how they can worsen coughing. In addition, this negative effect does not always manifest itself. On many occasions I have used cold showers when coughing is present without any problems. I use cold showers several times a day when I have a fever and they make me feel better: the most noticeable benefit is instant relief from fatigue, pain,
^U
and fever.
^W
The combination of fever-reducing drugs (such as acetaminophen) with adapted cold showers reduces fever and pain more effectively than either treatment alone. If the specific diagnosis is known (for example, if you have influenza), antiviral drugs will be helpful, in addition to fever-reducing treatments. Reducing or eliminating fever appears to be desirable during influenza illness because fever does not provide any known therapeutic benefit in viral infections. In bacterial infections fever can be beneficial [
408
,
409
]. Finally, studies show that fever-reducing treatments such as acetaminophen have no effect on the development of an immune response [
410
].

Self-experimentation suggests that when body temperature is normal, a 20°C (68°F) cold shower will not lower core body temperature even if the shower lasts 30 minutes. Paradoxically, normal core body temperature
increases
by about 0.1 to 0.2 degrees Centigrade (0.2 to 0.4°F) during a cold shower, consistent with some published studies [
343
,
378
]. The body increases heat production to defend normal core body temperature upon exposure to cold. On the other hand, if fever is present, core body temperature declines during the 20°C cold shower by about 0.2°C (0.4°F) every 5 minutes. The core body temperature declines by an additional 0.5°C (1°F) within an hour after you stop the procedure. This must be the result of the anti-inflammatory effect of moderate cooling.
^W
Yet the cold shower eliminates the
feeling
of being feverish, even though core body temperature is still elevated. On the other hand, adapted cold showers are extremely uncomfortable and impossible to use during chills, even if body temperature is above normal.

So far, nobody has tested the safety of the above approach in clinical trials, aside from studies two centuries ago [
357
,
571
]. I used this approach successfully with every fever that I have had since August 2005 (about once a year), except for the upper respiratory tract infection in March 2009. During that episode, cold showers eliminated most symptoms (fever, pain, and weakness), but coughing persisted and worsened (the specific diagnosis is unknown).

To be on the safe side, you need to avoid cold showers altogether when a cough is present. Use fever-reducing drugs instead, if necessary. Keep in mind that you should not use aspirin if you suspect that you have the flu—this is a risky combination. Acetaminophen is safe in most cases. If you have a cough and a fever and you are dying to try a cold shower, you can modify the adapted cold shower procedure to avoid wetting the neck and rib cage area. The modified cold shower procedure does not worsen coughing but it is more complicated. You skip the preliminary tepid shower, and when you start the gradual adaptation phase, you stop expanding the area of contact with cold water when you reach the chest area. You can then apply the cold shower to the arms, avoiding splashing water on the neck and rib cage area. You will cool the head afterwards using a separate procedure, the “head shower.” Do not take the preliminary warm shower because leaving wet skin in the open air cools the neck and chest area.