How to Sleep When It's Really Hot

[Onemoreproject]

It’s getting hot here in Baha. We sleep in V-berth under a 24 “ hatch with Windscoop, fans and damp towels over our torsos to keep cool. I learned that when sleeping under wet sheets in the bottom of the Grand Canyon.

[MSgt]

Had three Hella fans in Vberth of my Irwin citation 34. one forward towards the bow to blow towards me form my feet, and one in each corner near head, on blowing downwards at my head and the other aimed at my torso. With three blowing plus wetting my hair and body in the shower prior to going to bed kept me comfortable.

[GordMay]

My experience says that, darker colored boats [especially decks] get much hotter, than lighter ones; but, counter intuitively, and according to Consumer Reports test engineers [1], that may be a bit of an overstatement.
They measured the interior temperatures of two cars: One with a light-colored exterior and light-colored interior, and the other with a dark exterior and dark interior.
Both cars were parked outside, and started off with an interior temperature of 78F.
After an hour, the temperatures inside both cars had exceeded 100F, with the darker car being, only, a few degrees hotter.

The CR test engineers concluded [1] that “a light-colored interior is going to be slightly cooler, but when you’re talking over 100° F inside, it’s really hot either way.”

[1] “Do Cars With a Dark Interior Really Get Hotter in the Sun?”
The difference between dark and light interiors might not be as substantial as you think
➥ https://www.consumerreports.org/cars...n-a6491490288/

[Jamme]

Originally Posted by GordMay

Both cars were parked outside, and started off with an interior temperature of 78F.
After an hour, the temperatures inside both cars had exceeded 100F, with the darker car being, only, a few degrees hotter.

Could this have something to do with both cars being parked outside, presumably on (dark) asphalt, thereby absorbing heat also from the surroundings? Perhaps with boats being in the water, the temperature difference between dark and light colored boats could be more material?
Fair winds.

[GordMay]

Originally Posted by Jamme

Could this have something to do with both cars being parked outside, presumably on (dark) asphalt, thereby absorbing heat also from the surroundings? Perhaps with boats being in the water, the temperature difference between dark and light colored boats could be more material?
Fair winds.

Seems plausible, to me, but: Why did both cars heat up at roughly the same rate, and to nearly the same temperature? Because it is the car’s glass that causes a vehicle to warm up so rapidly, CR says.

[s/v Jedi]

Also, there is a big difference between a pure white deck and one that is slightly off white. A tiny bit of color results in much more heat.

[rossdv8]

From someone who has spent most of his life living in temperatures that are regularly well over 90 deg F, 30 deg C, that test with the cars was ridiculous.

Under test conditions, closed, in the sun and left without any ventilation? yes, both cars will get similarly hot inside.


Left with the windows down a couple of inches? The light car will still be hot, but not quite 'as hot'.


After spending some of my youth as a car salesman, and being forced to drive variously coloured cars in the tropics all year around on a two week rotation, it became obvious that the only cars that stayed significantly cooler in hot temperatures whether parked closed up were white cars with light interiors - preferably with light coloured cloth seat covers.


That was 'W H I T E', not 'off white, or cream!
I still drive a white Toyotas HiAce van that is 21 years old and that I have had for 16 years. I can drive it all year round and in the hottest weather I can get into the thing and not gasp for breath after it has sat in the sun. I also drive it all year round without air conditioning, because once the windows are down it cools rapidly.
Until it became restricted to town duties for lack of available cooling system parts, I was still going camping in it, and often sleeping in the back, on days over 30 degrees Cels.



The same went for every one of my yachts.
I experimented with leaving the cream or that awful light blue some boats had for deck and cabin tops when I bought them, but almost cooked inside, or had to wear shoes on deck to save the skin of my footsies.


My second last boat, I decided a touch of light grey mixed into the white paint would look great. That lasted two trips before I caved in and slopped a can of pure white across the lot.


Luckily, sailing through our Great Barrier reef and its islands means wearing Polaroid sunnies is a necessary thing here, so the glare wasn;t an issue.


Temperatures below decks in daytime are severely impacted by the temperature the deck and cabin surfaces heat up to.


Wander through a car yard around 1pm on a summer day - and feel the roofs and bonnets (or hoods or whatever you call the front bit in your language) and rest your hands on any horizontal surface that has been in the sun,


Write what your hand (the palm pressed flat) felt for each colour, in a notebook


It might surprise you :-)

[GordMay]

Humidity is the amount of water vapour in the air. High humidity makes people feel hotter, than they would on a drier day. This is because the perspiration that cools us down cannot evaporate as quickly, in moist, saturated air.
To better describe how hot it feels in such circumstances, Canadian meteorologists developed the Humidex, a parameter that combines temperature and humidity, in order to reflect the perceived temperature.

The body attempts to maintain a constant internal temperature of 37°C, at all times. In hot weather, the body produces sweat, which cools the body, as it evaporates. As the humidity [or moisture content] in the air increases, sweat does not evaporate as readily. Sweat evaporation stops entirely, when the relative humidity reaches about 90 percent. Under these circumstances, the body temperature rises, and may cause illness. The Humidex is a Canadian innovation that was first used in 1965.
It describes how hot, humid weather feels to the average person.
The Humidex combines the temperature and humidity , into one number, to reflect the perceived temperature.
Because it takes into account the two most important factors that affect summer comfort, it can be a better measure of how stifling the air feels, than either temperature or humidity alone.
Heat-related illnesses depend on many workplace factors, in addition to air temperature and humidity. Wind speed or air movement, workload, radiant heat sources, and a person's physical condition are also important.

According to Environment and Change Canada, a humidex in the mid to high 30s is when the average healthy person should be more careful.
Over 40 is considered extremely high, and all unnecessary physical activity should be avoided.

Range of Humidex: degree of comfort
20 to 29: Little discomfort
30 to 39: Some discomfort
40 to 45: Great discomfort; avoid exertion
Above 45: Dangerous; heat stroke possibleSee also:

See also:

“Warm season weather hazards”
➥ https://www.canada.ca/en/environment...ards.html#toc7

“Extreme Heat Events Guidelines: Technical Guide for Health Care Workers”
➥ https://www.canada.ca/en/health-cana...e-workers.html


"Wind Chill and Humidex Calculators"
➥ https://weather.gc.ca/windchill/wind_chill_e.html



HUMIDEX scores by air temperature [°C] and relative humidity

[Chotu]

Going back to paint color for a moment, or at least deck cooling, I found that once I installed my solar panels I achieved an even cooler deckhouse roof than the white paint.

my deck house roof has always been a source of too much heat. The heat rises naturally in a catamaran into the deck house and then if you have it radiating through the roof as well right about head level it’s pretty bad actually.

I started off with gray primer on the deck house roof and no solar panels. That was bad.

Next I painted the roof white non-skid that made a difference. A big difference.

Later, I added the solar panels and that really changed things as a large portion of the roof is covered in them.

I think the car color experiment has more to do with the fact that it’s a greenhouse effect through the windows. If you think about it, there isn’t really a lot of surface that is painted white or black or whatever on the car. That’s not the main ingress of heat. It’s from the windows.

This is different on a boat because the main ingress is through the painted hull. There are less windows. Lucky me, I have both. Ha ha. Mine heats up like a car through the windows and I have the regular boat heat transmission

[GordMay]

The human body's ideal temperature lies between 35.01°C and 37.76°C (95-99.9°F)[1], depending on how it is measured, although most medical experts accept an average of 36.8°C (98.2°F).
When the surrounding air nears or exceeds this temperature, particularly when humidity is high, the body's ability to cool itself weakens.
One study [2], from 2020, found the upper limit of what the human body can survive without serious health effects is a wet-bulb temperature of 35°C (95°F) – which is a measure of both temperature and humidity together. In high levels of humidity, it is harder for sweat to evaporate and so cool down.

The Centers for Disease Control and Prevention defines extreme heat as: “summertime temperatures that are much hotter and/or humid than average”, for a particular area. [3]

While the evidence on the colour of clothing is mixed: white clothing will reflect more light, but black clothes are better radiators of heat.
There appears to be little difference, between wearing light or dark clothing, as a study of Bedouin tribes, in the 1980s, revealed [4 interesting study].

Wearing loose-fitting clothes, like the robes favoured by the Bedouin, can help, by allowing air to circulate, next to your skin, and if you’re in direct sunlight, it’ll cut down on sunburn. If you have air circulating next to your skin, it will help to evaporate the perspiration, and this will make you feel cooler.

Standing under a freezing shower might sound like the quickest way to bring your temperature down, but your body will react to a dramatic change like this by trying to preserve heat; so a “lukewarm” shower might be better.
If I'm hot, and I go under a cold shower, I'll shut down the blood flow to the skin, and trap the heat inside me, rather than let it escape.

As a result, it's better to use water that is in the 20°s Celsius than water that is in the 10°s.
It's better to have a warmer shower, that is cool enough to lower the deep body temperature, but is warm enough, to allow your blood to the surface of the skin.

You've got four major arteries on your body, where the application of something cold, or hot, makes a great impact on your body temperature: your groin, armpits, and the back of your neck. The easiest one to chill is the back of your neck.
If you use a fan, make sure you direct the flow of air to your face & neck, because the face has so many receptors on it, it’s more effective. "Even though you're not cooling down your whole body, fanning your face has a disproportionate effect on your comfort.

If you only have a fan, some experts recommend misting yourself, with a spray bottle of cool water.
Generally, fans are thought to help, lower perceived temperatures, in temperatures up to 35°C (95°F), but above that, blowing hot air across the body could make the situation worse, and even increase dehydration. It's also worth remembering that fans use motors to work, and so generate some heat of their own, while running.

Drinking water before bed might help ward off dehydration, while you sleep, and it may also help you attain the drop in core body temperature, that helps induce sleepiness.
However, drinking too much water, before bed, contributes to nocturia [waking up to urinate, more than once a night], especially for people with certain conditions, such as kidney disease, or diabetes, or those who are taking diuretic medicines.
If you feel very thirsty before bed, you may want to drink a small glass of water, to help you get through the night.
However, the ideal is to stay hydrated throughout the day so you do not need to drink excessive amounts of water at bedtime.

If you haven’t already replaced your old-fashioned filament-style light bulbs, with LED lamps, do it now, for the sake of keeping cool. Energy-efficient LED lamps generate far less heat, than incandescent lamps.

[1] “Normal Body Temperature: A Systematic Review” ~ by Ivayla I Geneva et al
➥ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6456186/

[2] “The emergence of heat and humidity too severe for human tolerance” ~ by Colin Raymond et al
➥ https://www.science.org/doi/10.1126/sciadv.aaw1838

[3] “About Extreme Heat” ~ CDC
➥ https://www.cdc.gov/disasters/extrem...eat_guide.html

[4] “Why do Bedouins wear black robes in hot deserts?”
➥ https://www.nature.com/articles/2833...er=www.bbc.com

[GordMay]

Intermittent exposure to heat is also important, to help our bodies tolerate heat better, and even allow us to exercise, or sleep, in higher temperatures.
If we don't expose ourselves to heat, then we won't acclimatize, to it.

[GordMay]

Cooling the brain during sleep may be an easy, natural and effective treatment for insomnia

Researchers from the University of Pittsburgh School of Medicine reported at the 2011 annual meeting of the Associated Professional Sleep Societies (APSS) that keeping the brain cool may help people with insomnia to catch more z’s.[1]

According to the authors, a reduction in metabolism in the brain’s frontal cortex occurs while falling asleep, and is associated with restorative sleep. However, insomnia is associated with increased metabolism in this same brain region. One way to reduce cerebral metabolic activity is to use frontal cerebral thermal transfer, to cool the brain, a process known as “cerebral hypothermia.”

Dr. Daniel Buysse, a psychiatrist at the university, had already shown in previous studies [2] that those with insomnia tend to have higher than normal activity in the frontal lobes of their brains, the regions responsible for higher-order functions like planning, organizing and logical reasoning. Many insomniacs say they can’t fall asleep because their brains keep working, and they can’t shut off these thought processes. Buysse wondered whether the added activity was also raising the brain’s temperature to the point at which sleeping was physiologically more difficult. The body’s circadian clock, which regulates sleep and wakefulness, keeps the body at its warmest during the day and starts to lower body temperature in the evening to help us doze off. For those with insomnia, however, researchers found that the extra brain activity was keeping the brain too hot to sleep.

When Buysse’s group gave 12 insomniacs a soft plastic cap, that contained tubes, that were filled with circulating water, at cool temperatures, to wear, they were able to get them to fall asleep almost as easily as people without sleep disorders: using the caps, the insomniacs took about 13 minutes to fall asleep, compared with 16 minutes for the healthy controls, and they slept for 89% of the time they were in bed, which was similar to the amount of time the controls spent asleep.

“What this tells us about insomnia is that there are many ways to intervene,” says James Wyatt, director of the sleep disorders center at Rush University Medical Center and a spokesperson for the APSS. “We have in our armamentarium a variety of medications and cognitive behavioral treatments, but this opens the door to an entirely new third category of mechanism device treatments.”

Cooling off the brain makes sense, since melatonin, one of the more effective medications to help people sleep, also works in part by lowering body temperature.

More studies will have to confirm the results, and it’s not clear yet which patients may benefit the most from the cap, but for those who are uncomfortable with taking medication, or for whom existing treatments may not work, the cooling strategy may be helpful. In the study, those whose caps were set to the lowest temperatures were able to get more sleep, than those whose caps were slightly warmer.
Falling asleep, it seems, may simply be a matter of cooling off. Whodathunk?

[1] “Frontal cerebral thermal transfer as a treatment for insomnia: a dose-ranging study” ~ by E. Nofzinger & Daniel Buysse
➥ https://www.researchgate.net/publica...-ranging_study

[2] “Regional Cerebral Metabolic Correlates of WASO During NREM Sleep in Insomnia”
➥ https://jcsm.aasm.org/doi/10.5664/jcsm.26592

See also:
[3] “A novel forehead temperature-regulating device for insomnia: a randomized clinical trial” ~ by Thomas Roth et al

This study evaluated the safety and efficacy of a novel forehead temperature-regulating device that delivers frontal cerebral thermal therapy (maintained at 14–16°C, equivalent to 57–61°F) for the treatment of insomnia.
The main findings of this study are that acute two-night use of frontal cerebral thermal therapy has few side effects and produces improvements in insomnia patients’ ability to fall asleep. Additional studies are warranted to determine its role in the long-term management of insomnia.

➥ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5946849/

[aqfishing]

32 deg is crazy hot! If that was the case for good sleeping temp we wouldn't be having this discussion!!!

Is there a wind scoop that can let the air in, but not the rain?

[Andy - SV Indie]

We spent the winter in the Bahamas where it was between 24-32C (80Fplus). Some nights were crazy hot. We started out with a kids play tent that I had made into a wind scoop of sorts. I didn't wan to pay much at first as I was unsure how much air they really bring into the berths. It worked great but, when the wind changed direction I had to get up and move it around. With changing currents it was a hassle each day. In January I was at the boat show and saw a Breeze Bandit windscoop that clipped under our hatch and had a 360-degree airflow. I bought ($80 each) 2 (one for each hatch), they were life savers. We stayed in the heat till April and they kept the ventilation flowing in the sweltering heat.



We also had rechargeable fans and used rechargeable silicone dehumidifiers in and around the boat.



After 1 season all are still in good shape and to be honest we didnt have the solar power to have an air-conditioner and I am happy with our choices.

[GordMay]

Hurricane + Heat = A Double Whammy:

Hazards, indirectly related to storms, like exposure to heat, kill nearly as many people, as the storm itself, NOAA data [1] shows.
Nearly 22% of those, so-called, indirect deaths, were caused by heat and generator misuse, from 2013 to 2022.
Experts have also said that extreme heat is a silent killer, and can be a major contributing factor, in the overall hurricane death toll.
A study [2], published in the journal Nature Medicine, found that 61,672 died, in Europe, from heat-related illness, between May 30 and September 4 last year.

An intense hurricane, and extreme heat, could be a deadly combination, because storm destruction, and widespread power outages, would leave people exposed and vulnerable to heat.
When Hurricane ‘Irma’ pummeled Florida, in 2017, for instance, several people were killed, at a Hollywood nursing home, due to overheating, after the storm knocked out the air conditioning.

[1] NOAA, FEMA, and the American Red Cross presented the annual “Congressional Briefing on the 2023 Hurricane Season Outlook and Preparedness”, on Thursday, May 25, 2023.
➥ https://www.noaa.gov/sites/default/f...okBriefing.pdf

[2] “Heat-related mortality in Europe during the summer of 2022" ~ by Joan Ballester et al
➥ https://www.nature.com/articles/s41591-023-02419-z