Blowing hot and cold: How does the weather affect your mood and well-being?

Straits Times, 24 Dec 2024, Blowing hot and cold: How does the weather affect your mood and well-being?

The weather in Singapore has been blowing hot and cold. 

On Dec 7, the temperature in Paya Lebar reached 36.2 deg C, setting a record for the highest daily maximum temperature recorded in December. The previous high of 35.9 deg C was set in Seletar on Dec 6, 2016.

At the same time, frequent downpours, mainly due to the north-east monsoon season, made this the wettest November since rainfall data collection began in 1980, according to the Meteorological Service Singapore. 

Amid these extremes, have you noticed feeling more refreshed and energised on cool, breezy days compared with hot, humid ones? 

This is not just a feeling. There is a science behind how temperature affects your energy levels and overall well-being.

Dr Sarah Chan, a Chan Heng Chee Research Fellow at Singapore University of Technology and Design’s Lee Kuan Yew Centre for Innovative Cities, says cool days, being more comfortable and pleasant, help to maintain or promote positive emotions.

“When you’re in a good mood, you tend to feel more motivated and enthusiastic about what you are doing. Plus, it’s easier to enjoy and appreciate the smaller things in life,” she says.

Dr Chan is an environmental psychologist who studies the interactions between people and their environments. Her research focuses on how environmental sustainability, technology and urban development, and human well-being affect one another.

Cooler weather encourages people to spend more time outdoors, increasing opportunities for social interactions. This combination of physical comfort, positive mood and increased social engagement is invigorating and contributes to psychological well-being, says Dr Chan.

On the flip side, heat results in thermal discomfort, which can brew negative emotions.

“Physically, our bodies are busy with thermoregulation, while psychologically, we engage in emotional regulation to handle the strain caused by heat. This dual effort can feel draining, reducing focus and alertness,” says Dr Chan.

Heat adds an extra layer of exertion to any task. When it is hot, people perceive tasks to be more demanding than they really are. 

The physical discomfort and strain often lead to greater irritability and stress, making it more difficult to concentrate on tasks, she says.

Body’s energy level tied to temperature changes

Dr Leong Choon Kit, a family physician at Mission Medical Clinic, says that how energetic a person feels is influenced by his body’s response to temperature changes. 

In extremely hot weather, physical discomfort and dehydration slow down bodily functions, leading to fatigue or, in severe cases, heat exhaustion or heat stroke.

When you are exposed to heat, your body works hard to maintain homeostasis by dissipating the excess heat to outside your body, says Associate Professor Jason Lee, director of the Heat Resilience and Performance Centre at NUS Medicine.

Homeostasis is your body’s way of keeping things balanced and stable, like maintaining a steady temperature, heart rate or hydration level, no matter what is happening around you.

To cool down, your body increases blood flow to the skin and activates sweating.

“As a result, our heart rate increases, which can cause fatigue, especially for those with limited cardiovascular capacity, such as the elderly or those who are unfit,” says Prof Lee.

As blood is diverted to the skin to lose heat, vital organs such as the brain may receive less blood, potentially leading to lightheadedness or fainting, he says.

How chronic discomfort shapes behaviour and well-being

For people who are regularly exposed to heat in tropical climates like Singapore, the body does adapt to this thermal discomfort, he says. However, this often leads to reduced outdoor activity.

Chronic discomfort can cause people to avoid outdoor activities and reduce incidental physical activities, such as cycling or walking to work. Over time, this can contribute to a sedentary lifestyle, notes Prof Lee.

This may lead to broader health consequences, including poor cardiovascular health and mental health issues.

He also refers to Singaporeans and those living in the equatorial region, such as in Indonesia and Maldives, as having “boiling frog syndrome”, meaning they may fail to notice gradual, harmful changes until it is too late.

Prof Lee makes this reference in relation to how chronic exposure to heat has shaped behaviour in ways that affect health.

“Unlike other places where you can easily clock a number of steps just by commuting or walking around, here, the heat makes it harder to stay active,” he says. 

Cooler weather, on the other hand, allows the body to function more comfortably, promoting better rest and recovery, which contributes to feeling refreshed and energised, says Dr Leong. 

Heat can also disrupt sleep patterns, leading to fatigue the next day, but a well-ventilated or air-conditioned environment can help mitigate these effects, says Dr Leong.

Heat also affects cognitive function similarly to physical performance, as the body’s discomfort and the psychological strain of coping with heat can impair focus and mental energy. 

Cooler weather reduces these distractions, and hence supports better cognitive and physical functioning, says Dr Leong.

Use heat to your advantage

But heat is not always a bad thing. Dr Chan notes that hot weather comes with sunshine, which plays a vital role in boosting mood and well-being.

“Exposure to sunlight triggers the production of serotonin, also known as the ‘feel-good’ hormone, which helps to regulate our mood and reduce stress,” she says.

Despite Singapore’s heat, the sunny climate provides a consistent supply of this natural mood booster year-round.

Moreover, when used in moderation, Prof Lee says heat can be a helpful stressor that encourages positive changes in the body.

“Exposing the body to warm environments during exercise can elicit greater physiological strain. With sufficient recovery, it can stimulate the body to adapt and hence improve cardiovascular fitness,” he says.

Hot yoga is an example of using heat as a positive stressor. The practice involves performing yoga in a heated environment, typically between 35 and 40 deg C with high humidity.

This heat adds an extra layer of physical challenge by increasing heart rate, stimulating sweating, and requiring greater focus and mindfulness.

However, Prof Lee cautions against overdoing it. Like any other activity that exerts the body, progressive exposure is key. 

Practising without proper hydration or sufficient recovery can lead to heat-related issues such as dizziness or heat exhaustion, he notes.

To thrive in hot weather, learning to keep your cool – both physically and emotionally – can make all the difference.

Besides taking action to improve thermal comfort, such as wearing cooling clothing and staying hydrated, strategies that support emotional regulation are equally important, says Dr Chan.

“Breathing exercises can activate our body’s parasympathetic nervous system, promoting calmness by reducing stress,” she says.

Mindfulness practices can also reduce irritability and improve emotional resilience, helping you stay grounded.

“Reminding yourself that tasks are likely less demanding than they feel in the moment eases perceived effort and the mental load. Small distractions like listening to music can be emotionally uplifting and restore energy levels,” says Dr Chan.