{"id":180,"date":"2025-09-23T05:11:05","date_gmt":"2025-09-23T05:11:05","guid":{"rendered":"https:\/\/users.utu.fi\/lihsun\/?p=180"},"modified":"2025-09-23T05:11:05","modified_gmt":"2025-09-23T05:11:05","slug":"when-the-days-grow-shorter-how-to-stay-well","status":"publish","type":"post","link":"https:\/\/users.utu.fi\/lihsun\/2025\/09\/23\/when-the-days-grow-shorter-how-to-stay-well\/","title":{"rendered":"When the days grow shorter: how to stay well"},"content":{"rendered":"

Today marks the\u00a0autumn equinox<\/strong>\u00a0\u2014 the point in the year when day and night are of equal length. From now on, the nights will steadily outgrow the days, and here in the north we will soon find ourselves waking in the dark and leaving work under the same twilight. For many people this change is simply part of the rhythm of the seasons. But for some, it brings fatigue, cravings for comfort food, and even depression. This recurring pattern is known as\u00a0seasonal affective disorder (SAD)<\/strong>.<\/p>\n

\"\"<\/p>\n

As a researcher at the Turku PET Centre, I have been studying how our brain and body adapt to changing seasons. My work focuses on the\u00a0mu-opioid receptor (MOR) system<\/strong>, which plays a central role in regulating mood, social bonding, and the sense of reward. What we are finding is that the shortening of days doesn\u2019t just affect sleep patterns \u2014 it also changes how our brain and body respond to the world.<\/p>\n

The biology of shorter days<\/strong><\/p>\n

Light is the main timekeeper for the human body. It sets our daily rhythms, influences sleep, and regulates hormone release. But light also affects how the\u00a0brain\u2019s chemical systems<\/strong>\u00a0function. My research shows that MORs, which respond to the brain\u2019s natural opioids, change their availability depending on the season.<\/p>\n

In summer, when the days are long, MOR availability is relatively high in certain brain regions that regulate emotions and social behaviour. In winter, as daylength shortens, MOR availability declines. This may explain why many people feel less motivated, less social, and more vulnerable to low mood during the darker months.<\/p>\n

A brain\u2013body story: the role of brown fat<\/strong><\/p>\n

What surprised us was that these changes are not limited to the brain. We also found that\u00a0brown adipose tissue (BAT)<\/strong>\u00a0\u2014 a special type of fat that helps generate heat \u2014 shows seasonal shifts in MOR signalling. In shorter days, MOR activity in BAT increases and the interaction between BAT and brain is strengthend.<\/p>\n

This suggests that the brain and brown fat may be working together, coordinated through the opioid system, to help the body adapt to the cold and to the lack of light. While BAT takes care of generating warmth, the brain adjusts mood and behaviour. In this way, our whole body participates in seasonal adaptation. The downside is that these adaptations may leave some people more vulnerable to\u00a0seasonal depression, responsible for addictive consumption of heavy food.<\/p>\n

Supporting mood and resilience in winter<\/strong><\/p>\n

The good news is that there are practical steps we can take \u2014 grounded both in clinical research and in what we are learning from brain imaging studies.<\/p>\n

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  1. Light exposure<\/strong><\/li>\n<\/ol>\n

    The most effective and evidence-based method is\u00a0bright-light therapy<\/strong>. Sitting in front of a light box for short period each morning helps reset the body clock and stimulates brain circuits that improve mood and energy. For many people, this alone can prevent or relieve symptoms of seasonal depression.<\/p>\n

    Even without a light box, getting outside in the morning \u2014 especially on clear days \u2014 makes a big difference. Natural daylight, even when it looks dim, is far brighter than indoor lighting.<\/p>\n

      \n
    1. Regular routines<\/strong><\/li>\n<\/ol>\n

      Keeping a steady rhythm of waking, eating, and sleeping supports the body\u2019s adaptation to the season. Our brains like predictability, and regular routines help stabilise mood.<\/p>\n

        \n
      1. Exercise and movement<\/strong><\/li>\n<\/ol>\n

        Physical activity is one of the most powerful natural ways to stimulate the brain\u2019s opioid system. Running, brisk walking, dancing, or even moderate exercise releases endorphins, which bind to MORs and boost mood. Exercising outdoors gives the added benefit of light exposure.<\/p>\n

          \n
        1. Social connection<\/strong><\/li>\n<\/ol>\n

          MORs are not only about reward from exercise or food \u2014 they are also deeply tied to social bonding. Laughter, shared meals, warm touch, and time spent with friends or family naturally activate this system. In winter, when our biology may make us withdraw, it is even more important to plan social contact deliberately.<\/p>\n

            \n
          1. Eating with the season<\/strong><\/li>\n<\/ol>\n

            Food also connects us to the seasonal cycle. Eating local and seasonal produce \u2014 root vegetables, cabbages, berries stored from summer, hearty grains \u2014 not only supports sustainable habits but may help us feel more grounded in the rhythm of nature. Cooking warm, nutritious meals together can also provide social comfort and activate the brain\u2019s reward systems in a healthy way.<\/p>\n

            Why My Research Points to Natural Strategies<\/strong><\/p>\n

            Because the mu-opioid system is central to how we experience reward and pleasure, it is tempting to ask: could medicines that act on opioid receptors help seasonal depression? The answer is NO<\/strong> \u2014 at least not with the drugs we normally think of as opioids. They carry major risks of dependence and are not appropriate treatments for mood problems.<\/p>\n

            Instead, the safer and more effective approach is to\u00a0support the body\u2019s own opioid system<\/strong>. Exercise, social contact, music, laughter, warmth, and meaningful activity all increase natural opioid release and receptor activity. In this sense, everyday choices can act as natural \u201cantidepressants,\u201d especially when the days grow short.<\/p>\n

            Looking ahead<\/strong><\/p>\n

            My work at Turku PET Centre has only begun to map how light, brain chemistry, and body metabolism interact across the seasons. By studying both the\u00a0brain and brown fat<\/strong>, we are seeing a picture of seasonal adaptation that involves the whole body, not just the mind.<\/p>\n

            This perspective can also shift how we think about prevention. Seasonal depression is not simply a matter of willpower or \u201chating the dark.\u201d It is a biological response shaped by evolution, meant to conserve energy and adjust behaviour. The challenge for us, living in modern societies, is to work with our biology rather than against it.<\/p>\n

            Light therapy, exercise, social connection, seasonal foods, and healthy routines are not just lifestyle tips \u2014 they are ways of\u00a0nudging our opioid and circadian systems back into balance\u00a0when the environment is stacked against us.<\/p>\n

            Final thoughts<\/strong><\/p>\n

            On this equinox, when day and night stand equal, we are reminded of the turning point of the year. From now on, darkness will gradually outweigh light, and our bodies and minds will begin their seasonal adjustment.<\/p>\n

            My research shows that the brain\u2019s mu-opioid receptor system, together with brown adipose tissue, shifts its activity with the seasons. This helps explain why winter feels different, and why some people are more vulnerable to seasonal affective disorder.<\/p>\n

            But it also gives us tools: by supporting our natural systems with light, movement, social contact, sustainable habits, and seasonal foods, we can reduce the risk of seasonal depression. In doing so, we are not fighting biology \u2014 we are helping it do its job in a world where winter light is scarce.<\/p>\n

            \ud83c\udf31<\/strong> Take-home message: 5 ways to stay well after the equinox<\/strong><\/p>\n

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            1. Seek light<\/strong>: get outside each morning or use a light box.<\/li>\n
            2. Move daily<\/strong>: exercise outdoors when possible, even short walks.<\/li>\n
            3. Stay social<\/strong>: schedule regular contact with friends or family.<\/li>\n
            4. Eat seasonal foods<\/strong>: enjoy local produce and warming meals.<\/li>\n
            5. Keep routines<\/strong>: wake, sleep, and eat at regular times.<\/li>\n<\/ol>\n\t\t