Your Body’s Not Broken - It’s Just Winter

If your winter period feels heavier, moodier, or just off, take a breath. Nothing’s gone wrong. Your body’s responding exactly how a human body does when the days get shorter and the light disappears by 4pm. To help us make sense of it all, this piece is written by Alison Bladh - a women’s health expert who specialises in how hormones, circadian rhythms, and lifestyle actually play out in real bodies.

Alison’s work bridges solid science with practical, compassionate guidance, helping people understand their cycles without panic or pressure. She’s not here to tell you to “fix” your hormones. - she’s here to explain what they’re doing, and how to support them gently through the colder months.

How do shorter days and reduced sunlight impact the menstrual cycle, hormonally speaking?

Light is one of the strongest regulators of your circadian rhythm, your internal body clock. In simple terms, daylight tells the brain when to feel alert and when to feel sleepy. When days are shorter, mornings are darker and evenings are longer, that light signal weakens and the timing can shift.

One of the main hormones affected is melatonin, which rises in the evening to help you fall asleep. In winter, melatonin can start rising earlier and stay higher for longer because your body is getting more darkness overall. That can change sleep timing and sleep quality and it can also influence the hypothalamus in the brain, the area that coordinates reproductive hormones.

Sleep and light patterns also influence cortisol, your key stress and energy hormone. Cortisol should naturally peak in the morning and fall through the day. When light exposure and sleep are disrupted, cortisol can become higher, flatter, or more erratic. This matters because cortisol interacts with the reproductive hormone system. If the brain is reading the environment as stressful or out of rhythm, it can reduce or alter the signals that drive ovulation and stable cycle patterns, which can show up as changes in cycle length, PMS, cravings, mood swings, or more painful periods in some women.

Winter can also affect vitamin D status, especially in northern climates, because UVB sunlight exposure is low. Vitamin D receptors are found in reproductive tissues and low vitamin D levels have been associated with worse period pain in some studies. It is not the only factor, but it is a relevant one, particularly if someone is already prone to cramps or low mood. It is also worth noting the knock-on effects of winter habits. People often move less, feel more stressed, eat differently, drink more alcohol socially and spend more time indoors with artificial light and screens, all of which can further disrupt sleep and stress physiology. 

So overall, it is less that winter directly switches hormones off and more that light, sleep, stress, activity and nutrient status shift together and the menstrual cycle can be sensitive to that combined change.

Why might some people experience heavier, longer, or more painful periods in winter?

For some women, winter can act like a magnifying glass on whatever is already going on in the body. It is not that the season directly causes a menstrual problem, but the winter lifestyle shift can nudge a few key drivers of period symptoms. Less daylight and disrupted sleep are a big one.

Dark mornings and long evenings often mean later bedtimes, more screen time and lighter, more broken sleep. When sleep is off, cortisol can run higher or become more erratic and that tends to amplify PMS symptoms, sugar cravings, water retention and pain sensitivity. Many women also notice they feel more anxious or more emotionally reactive in winter, which can make period symptoms feel more intense overall.

Movement usually drops too, even in women who are generally active. When you move less, pelvic circulation can be poorer, bowel motility can slow and muscle stiffness increases. That matters because cramps are partly about uterine muscle contractions and when the whole system is tense, pain can feel sharper. Regular walking, gentle strength training and mobility work can genuinely change how a period feels. 

Food choices also often change in winter. We tend to reach for more refined carbohydrates, ultra processed foods and sugary treats, plus more caffeine and alcohol around social events. That combination can increase inflammation and affect blood sugar stability. In practical terms, it can mean more bloating, more headaches, more breast tenderness and cramps that feel harder to manage. Blood sugar swings also affect mood and fatigue, which makes the whole luteal phase feel tougher.

Vitamin D status can be a factor too. In northern climates, levels often dip in winter because UVB exposure is low. Vitamin D is involved in immune and inflammatory regulation, and low status has been linked with worse period pain in some women. This does not mean everyone needs supplements, but it does mean checking levels can be helpful if symptoms worsen seasonally.

Finally, cold exposure can increase muscle tension and make the nervous system more “guarded.” If you are already prone to cramps, low back pain or endometriosis type pain, winter stiffness can add another layer of discomfort. 

The key message is that not everyone notices a winter shift, and seasonal changes should not be used to dismiss symptoms. But for women who do feel worse in the colder months, it is usually the combined impact of sleep, stress, movement, nutrition, alcohol, vitamin D and overall inflammation, rather than one single hormone suddenly going wrong.

 Are teens more sensitive to seasonal hormone shifts? and if so, why?

Yes, many teenagers are more sensitive and a big reason is how puberty affects their internal body clock. During adolescence, the circadian rhythm naturally shifts later. This means the brain releases melatonin, the hormone that helps us feel sleepy, later in the evening compared to childhood and adulthood. In simple terms, teens are biologically wired to feel alert later at night and struggle more with early bedtimes.

In winter, this natural delay is pushed even further. Dark mornings reduce the light signal that helps reset the body clock each day, while long evenings, artificial lighting and screen use suppress melatonin even more. At the same time, school start times usually stay early. The result is a chronic mismatch between a teenager’s biology and their daily schedule, leading to ongoing sleep restriction and irregular sleep patterns. 

This matters for menstrual health because sleep and circadian rhythm play a key role in regulating stress hormones and reproductive hormone signalling between the brain and the ovaries. When sleep is shortened or inconsistent, cortisol patterns can become disrupted and this can interfere with the finely tuned hormone communication that supports regular ovulation and predictable cycles. In teens whose cycles are still developing in the first few years after menarche, this system is already less stable, so it is more easily affected.

As a result, some teens may notice more irregular periods, heavier or more painful bleeding, worse PMS or increased fatigue and mood changes during winter months. It does not mean something is wrong, but it does highlight how important sleep timing, light exposure and stress management are for adolescent menstrual health, particularly in darker seasons.

What lifestyle changes or habits can help support hormone balance in winter months?

In winter, the most helpful approach is not perfection but consistency. Small, repeated habits that support your body clock, stress response and blood sugar can make a noticeable difference to how you feel across the month. These are the key foundations I encourage.

Morning daylight is one of the most powerful and underestimated tools. Getting outside for 10 to 20 minutes soon after waking, even on grey or cloudy days, helps anchor your circadian rhythm. This light signal tells the brain when the day has started, supports healthy cortisol release in the morning and helps melatonin switch on at the right time later that evening. This can improve sleep quality, energy and cycle regularity. Protecting sleep becomes even more important in darker months. 

Try to keep sleep and wake up times as consistent as possible, even at weekends. Dim lights in the evening, reduce overhead lighting and aim to switch screens off earlier when you can. These small changes help melatonin rise naturally and reduce the stress hormone load that can worsen PMS and cramps.

Balancing blood sugar is another cornerstone. A protein rich breakfast, fibre from vegetables, fruit and whole foods, and regular meals during the day help prevent big glucose swings. When blood sugar is steadier, cravings, irritability, fatigue and anxiety tend to ease and hormones such as cortisol and insulin are less likely to interfere with reproductive hormone signalling. 

Daily movement is also essential, but it does not need to be intense. A brisk walk, gentle strength work or mobility exercises improve insulin sensitivity, circulation and mood and can reduce period pain by improving blood flow and reducing muscle tension. In winter, movement also supports mental health and energy when motivation can be lower.

As already mentioned, Vitamin D is worth considering, particularly in northern climates. Levels often drop in winter due to lack of sunlight and vitamin D plays a role in immune regulation and inflammation. A blood test can help guide whether supplementation is appropriate, rather than guessing.

Including magnesium rich foods such as leafy greens, nuts, seeds, beans and cacao can also be supportive. Magnesium helps calm the nervous system, supports muscle relaxation and can ease cramps and sleep difficulties for some women.

It is also worth mentioning alcohol, especially over winter. Alcohol can fragment sleep, increase night waking and worsen anxiety for some, even if it helps you fall asleep initially. It can also increase sugar cravings and inflammation, which may make PMS and cramps feel more intense. Keeping alcohol occasional rather than the default and swapping in alcohol free options can make a real difference.

If someone is experiencing heavier periods, iron becomes important too. Losing more blood can deplete iron stores over time, which can worsen fatigue, low mood, breathlessness, poor concentration and feeling cold. Including iron rich foods regularly, such as lentils, beans, eggs, sardines, red meat, spinach and pumpkin seeds and pairing them with vitamin C rich foods like peppers, citrus or berries to improve absorption, is a smart winter strategy. If symptoms suggest low iron, it is worth checking ferritin with a clinician rather than guessing.

Finally, connection matters more than we often realise. Winter can be isolating and reduced social contact can increase stress hormones and low mood, both of which can affect the menstrual cycle. Making an effort to connect with others, whether that is a walk with a friend, a class, a shared meal or simply regular check ins, provides emotional regulation and nervous system safety. Feeling supported and connected is not just good for mental health, it has a real physiological effect on stress hormones and overall hormonal balance. Together, these habits support circadian rhythm, stress regulation and inflammation, which is where many winter related period issues begin.

When should someone consider seeing a doctor about winter related period changes?

• Bleeding between periods, after sex, or any bleeding after menopause
• Very heavy bleeding, Soaking through pads or tampons frequently, needing to change protection overnight, passing large clots, or bleeding that repeatedly lasts longer than about 7 days
• Severe pain that is new, worsening, one sided, or not relieved by usual measures
• Possible symptoms of anaemia, such as marked fatigue, dizziness, breathlessness, palpitations, headaches or looking unusually pale
• A noticeable change in your cycle pattern that persists for three cycles or more, particularly if there is pelvic pain, unusual discharge, fever, or unintended weight loss
• Any chance of pregnancy, including concern about ectopic pregnancy if pain is sharp, one sided, or accompanied by spotting

The bottom line is this: seasonal shifts can play a role, but persistent, severe, or unusual symptoms deserve proper assessment. If in doubt, get checked.

Your Cycle’s in Winter Mode - And That’s Okay

Winter asks more of us, hormonally and emotionally. Less light, more fatigue, disrupted routines - and your menstrual cycle is sensitive to all of it. That doesn’t mean you need to push harder or power through. It means your body is nudging you to slow down, warm up, and respond with care instead of criticism.

Understanding how seasons affect your hormones isn’t about control - it’s about compassion. When you work with your cycle instead of fighting it, things often feel a little steadier. A little kinder. And a lot more manageable.

So if your period feels different in winter, let this be your permission slip: to rest more, to need support, and to trust that your body knows what it’s doing. You don’t need to override winter.
You just need to listen to what your body’s asking for.

Related posts

Understanding Your Menstrual Cycle 

What is Hormone Imbalance?

What is PMS?

Super Heavy Period at Christmas: Here’s What You Need to Know

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