The annual pattern of winter depression and melancholy – better known as seasonal affective disorder, or SAD – suggests a strong link between your mood and the amount of light you get during the day.

To put it simply: The less light exposure one has, the more one’s mood may decline.

Wintertime blues are common, but about 10 million Americans are affected every year by a longer lasting depression called seasonal affective disorder. Along with low mood, symptoms include anxious feelings, low self-esteem, longer sleep duration, constant craving for carbohydrates and low physical activity levels.

I am a nutritional neuroscientist, and my research focuses on the effects of diet and lifestyle factors on mood and brain functions such as mental distress, resilience and motivation.

Through my research, I have learned that seasonal affective disorder can strike anyone. However, people with a history of mood disorders are at a higher risk. In particular, young adults and women of all ages have an increased susceptibility.

Why seasonal depression happens

When daylight saving time ends each fall, the one-hour shift backward reduces the amount of light exposure most people receive in a 24-hour cycle. As the days get shorter, people can experience general moodiness or a longer-term depression that is tied to a shorter exposure to daylight.

This happens due to a misalignment between the sleep-wake cycle, eating schedules and other daily tasks. Research shows that this mismatch may be associated with poor mental health outcomes, such as anxiety and depression.

Our sleep-wake cycle is controlled by the circadian rhythm, an internal clock regulated by light and darkness. Like a regular clock, it resets nearly every 24 hours and controls metabolism, growth and hormone release.

When our brain receives signals of limited daylight, it releases the hormone melatonin to support sleep – even though we still have hours left before the typical bedtime. This can then affect how much energy we have, and when and how much we eat. It can also alter the brain’s ability to adapt to changes in environment. This process, called neuronal plasticity, involves the growth and organization of neural networks. This is crucial for brain repair, maintenance and overall function.

It is possible to readjust the circadian rhythm to better align with the new light and dark schedule. This means getting daylight exposure as soon as possible upon waking up, as well as maintaining sleep, exercise and eating routines that are more in sync with your routine prior to the time change. Eventually, people can gradually transition into the new schedule.

The intimate connection between serotonin and melatonin

Serotonin is a chemical messenger in the brain that is a key player in regulating several functions such as mood, appetite and the circadian rhythm. Serotonin also converts to melatonin with lower light intensity. As mentioned above, melatonin is a hormone that regulates the sleep-wake cycle and signals the brain that it’s time to sleep.

Less daylight exposure during winter months leads to the conversion of serotonin into melatonin earlier in the evening, since it gets dark earlier. As a result, this untimely melatonin release causes a disruption in the sleep-wake cycle. For some people this can cause moodiness, daytime sleepiness and loss of appetite regulation, typically leading to unhealthy snacking. People with seasonal affective disorder often crave foods rich in simple sugars, such as sweets, because there is an intimate connection between carbohydrate consumption, appetite regulation and sleep.

Strategies to combat the winter blues

In winter, most people leave work when it’s turning dark. For this reason, light therapy is typically recommended for those who experience seasonal affective disorder, or even shorter periods of seasonal funk.

This can be as simple as getting some light shortly after awakening. Try to get at least one hour of natural light during the early morning hours, preferably about one hour after your usual morning wake-up time when the circadian clock is most sensitive to light. This is true no matter what your wake-up time is, as long as it’s morning. For people living at northern latitudes where there’s very little sun in winter, light therapy boxes – which replicate outdoor light – can be effective.

You can also improve your sleep quality by avoiding stimulants like coffee, tea or heavy meals close to bedtime. Exercising during the day is also good – it increases serotonin production and supports circadian regulation. A balanced diet of complex carbs and healthy proteins supports steady serotonin and melatonin production, and practicing downtime before bed can reduce stress.

Taking these small steps may help the circadian rhythm adjust faster. For the millions with mood disorders, that could mean happier times during what are literally the darkest days.

Lina Begdache, Associate Professor of Health and Wellness Studies, Binghamton University, State University of New York

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Every year somewhere between 25 million and 30 million Christmas trees are sold in the United States. If you’re one of the people who decorate for the holiday with a freshly cut Christmas tree, you might be wondering how to keep it looking good all the way through Santa’s visit – and maybe even a little beyond.

Curtis VanderSchaaf is a forestry specialist at the Mississippi State University Extension Service who knows a thing or two about conifers. The Conversation U.S. asked him for guidance on how to keep a fresh green Christmas tree from becoming a giant pile of brown needles, for as long as possible. Whether you end up with a Douglas fir, a Scotch pine, a Leyland cypress, a piñon or any other evergreen, he says the quality of care you provide is a major factor in the prolonged freshness of your tree.

What to consider when choosing a tree

Select a tree that looks fresh and whose needles are not brittle. You want one that has a strong fragrance and a dark natural green color. Avoid bored holes in the wood, signs of bugs – like spider egg sacs – and other marks of pest damage. This advice holds whether you’re chopping down your own tree or buying it from a retailer.

Different species of trees have various colors, shapes, branching habits, needle types, scent and even bark type. Depending on what’s available to you, this comes down to personal preference.

If you can, pick a tree that’s been harvested as recently as possible and been watered and kept cool. Often a tree’s freshness is directly related to the moisture content of its needles. If the stump – where the tree’s trunk was cut – is sticky with sap, that’s a good sign.

Give the tree a good shake, even a hard pound on the ground. That will dislodge any animal stowaways. If a ton of dead needles or dry limbs fall out, keep looking.

Getting your tree home

Tree farms and retail lots will net your tree. It’s a lot easier to transport with the branches tucked in. If you’re going to bring it home on top of your car, consider using a tarp to keep scratches and sap off your vehicle. Make sure the tree is securely tied down, with the trunk facing forward to reduce wind damage to the branches. Take it easy on the road.

If you’re not bringing your tree indoors right away, store it in a cool, damp area that is blocked from wind and out of the sun.

Make a fresh, straight-across cut on the butt of the tree about a half-inch to 1 inch (1 to 3 centimeters) above the original cut. After any cut, a tree tries immediately to seal off, or compartmentalize, the injury, which makes it hard for the tree to take up water. So as soon as you make the new cut, place the tree in a bucket of warm water. Make sure it stays full as the tree drinks.

If you have allergies, you may want to spray the tree with a garden hose to remove residual pollen or dust – as long as the weather’s not freezing.

Setting up your tree inside

To keep a cut tree fresh you need to provide adequate water. Use a tree stand with a built-in reservoir, and make sure it’s always filled. A rule of thumb is 1 quart of water per inch of stem diameter. A freshly cut tree may use one-half to 2 gallons of water the first day, but this amount will taper as the tree acclimates to its indoor environment.

You don’t need to worry about adding anything to the water. It seems to just be an old wives’ tale that anything – including corn syrup, aspirin, vodka, soda pop, sugar or any specialized preservatives or gels – beyond H₂0 helps prolong the freshness of the tree. No special temperature is necessary either, just not freezing cold or boiling hot.

Do not drill a hole in the bottom of the tree trunk thinking it will improve water uptake – it doesn’t.

If you have to whittle down the sides of the trunk to fit, the tree is too large for your stand. It’s the outer layers of wood that take up most of the water, so if you shave them off your tree will be in trouble.

Secure the tree in its stand, ensuring the freshly cut stump is submerged. If it’s ever out of the water for more than about a quarter-hour or so, the cut starts the healing and sealing process and you should think about making a new cut.

Keeping the tree fresh into the New Year

Once your tree is all set up, your goal is to keep it from drying out. Remember, you want your tree to be fresh, but more importantly you don’t want to create a fire hazard.

Keep the tree at least 3 feet (1 meter) from any heat source and minimize direct sun exposure. Lowering the temperature in the room may also help to maintain freshness.

Make sure any lights and their cords are in good condition and turn them off when you aren’t present. Unplug completely if you are leaving the house or going to bed. Occasional breaks from using the lights may help slow the tree’s drying-out process. And make sure your smoke detectors work and you have a fire extinguisher on hand just in case.

If properly cared for, a fresh tree will last for three to four weeks, often even five. If it starts to get dry at any point, the safest move is to get rid of it. Chipping it for compost is the most environmentally sustainable option when it’s time for the tree to go.

Then you can start enjoying the lengthening days and look forward to the next holiday on your calendar.

Curtis VanderSchaaf, Assistant Professor of Forestry, Mississippi State University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

The International Space Station is no longer the only place where humans can live in orbit.

On Nov. 29, 2022, the Shenzhou 15 mission launched from China’s Gobi Desert carrying three taikonauts – the Chinese word for astronauts. Six hours later, they reached their destination, China’s recently completed space station, called Tiangong, which means “heavenly palace” in Mandarin. The three taikonauts replaced the existing crew that helped wrap up construction. With this successful mission, China has become just the third nation to operate a permanent space station.

China’s space station is an achievement that solidifies the country’s position alongside the U.S. and Russia as one of the world’s top three space powers. As scholars of space law and space policy who lead the Indiana University Ostrom Workshop’s Space Governance Program, we have been following the development of the Chinese space station with interest.

Unlike the collaborative, U.S.-led International Space Station, Tiangong is entirely built and run by China. The successful opening of the station is the beginning of some exciting science. But the station also highlights the country’s policy of self-reliance and is an important step for China toward achieving larger space ambitions among a changing landscape of power dynamics in space.

Capabilities of a Chinese station

The Tiangong space station is the culmination of three decades of work on the Chinese manned space program. The station is 180 feet (55 meters) long and is comprised of three modules that were launched separately and connected in space. These include one core module where a maximum of six taikonauts can live and two experiment modules for a total of 3,884 cubic feet (110 cubic meters) of space, about one-fifth the size of the International Space Station. The station also has an external robotic arm, which can support activities and experiments outside the station, and three docking ports for resupply vehicles and manned spacecraft.

Like China’s aircraft carriers and other spacecraft, Tiangong is based on a Soviet-era design – it is pretty much a copy of the Soviet Mir space station from the 1980s. But the Tiangong station has been heavily modernized and improved.

The Chinese space station is slated to stay in orbit for 15 years, with plans to send two six-month crewed missions and two cargo missions to it annually. The science experiments have already begun, with a planned study involving monkey reproduction commencing in the station’s biological test cabinets. Whether the monkeys will cooperate is an entirely different matter.

Science and a steppingstone

The main function of the Tiangong station is to perform research on life in space. There is a particular focus on learning about the growth and development of different types of plants, animals and microorganisms, and there are more than 1,000 experiments planned for the next 10 years.

Tiangong is strictly Chinese made and managed, but China has an open invitation for other nations to collaborate on experiments aboard Tiangong. So far, nine projects from 17 countries have been selected.

Although the new station is small compared to the 16 modules of the International Space Station, Tiangong and the science done aboard will help support China’s future space missions. In December 2023, China is planning to launch a new space telescope called Xuntian. This telescope will map stars and supermassive black holes among other projects with a resolution about the same as the Hubble Space Telescope but with a wider view. The telescope will periodically dock with the station for maintenance.

China also has plans to launch multiple missions to Mars and nearby comets and asteroids with the goal of bringing samples back to Earth. And perhaps most notably, China has announced plans to build a joint Moon base with Russia – though no timeline for this mission has been set.

Astropolitics

A new era in space is unfolding. The Tiangong station is beginning its life just as the International Space Station, after more than 30 years in orbit, is set to be decommissioned by 2030.

The International Space Station is the classic example of collaborative ideals in space – even at the height of the Cold War, the U.S. and the Soviet Union came together to develop and launch the beginnings of the space station in the early 1990s. By comparison, China and the U.S. have not been so jovial in their orbital dealings.

In the 1990s, when China was still launching U.S. satellites into orbit, concerns emerged that China was accidentally acquiring – or stealing – U.S. technology. These concern in part led to the Wolf Amendment, passed by Congress in 2011, which prohibits NASA from collaborating with China in any capacity. China’s space program was not mature enough to be part of the construction of the International Space Station in the 1990s and early 2000s. By the time China had the ability to contribute to the International Space Station, the Wolf Amendment prevented it from doing so.

It remains to be seen how the map of space collaboration will change in the coming years. The U.S.-led Artemis Program that aims to build a self-sustaining habitat on the Moon is open to all nations, and 19 countries have joined as partners so far. China has also recently opened its joint Moon mission with Russia to other nations. This was partly driven by cooling Chinese-Russian relations but also due to the fact that because of the war in Ukraine, Sweden, France and the European Space Agency canceled planned missions with Russia.

As tensions on Earth rise between China, Russia and the West, and some of that jockeying spills over into space, it remains to be seen how the decommissioning of the International Space Station and operation of the Tiangong station will influence the China-U.S. relationship.

An event like the famous handshake between U.S. astronauts and Russian cosmonauts while orbiting Earth in 1975 is a long way off, but collaboration between the U.S. and China could do much to cool tensions on and above the Earth.

Eytan Tepper, Visiting Assistant Professor of Space Governance, Indiana University and Scott Shackelford, Professor of Business Law and Ethics, Indiana University

This article is republished from The Conversation under a Creative Commons license. Read the original article.