Seasonal Changes and Your Hormones

As daylight hours shorten and routines change, it is common to notice shifts in sleep, energy, mood and appetite. This is not simply “autumn tiredness”. Light exposure, circadian rhythm, stress and nutrition all influence systems involved in hormone regulation.

Why autumn can feel different

Light is one of the main signals that sets your circadian rhythm - the internal 24-hour clock that helps regulate sleep, alertness and hormone release.

Reduced morning light and earlier darkness can affect the timing of melatonin, the hormone that signals to the body that it is time to sleep. This may mean feeling tired earlier in the evening, finding darker mornings harder, or feeling less alert at the start of the day.

Seasonal changes can also affect mood. Sunlight helps support vitamin D production in the skin, while lower daylight exposure is associated with seasonal changes in serotonin activity. Serotonin is involved in mood, appetite and sleep regulation, which may help explain why some people notice lower motivation, comfort-food cravings or more pronounced mood changes during autumn and winter.

Stress, cortisol and your routine

Autumn can also bring changes in routine - returning to work or education, busier schedules, reduced outdoor time and end-of-year pressure.

Stress activates the hypothalamic-pituitary-adrenal, or HPA, axis. This system regulates cortisol, a hormone involved in the body’s stress response, blood-sugar regulation, immune function and energy availability.

Cortisol follows a daily pattern. It is usually highest shortly after waking and gradually falls across the day. Poor sleep, irregular meals, ongoing stress and inconsistent light exposure can all interfere with this rhythm. When that happens, you might feel tired in the morning but mentally switched on at night, rely more heavily on caffeine, or experience disrupted sleep.

Why PMS may feel more noticeable

The menstrual cycle does not operate separately from the rest of the body. Sleep, stress, nutrition and energy intake can all influence how you experience different phases of your cycle.

For some women, the combination of reduced daylight, higher stress and poorer sleep can make PMS symptoms feel more intense. This can include fatigue, irritability, low mood, disrupted sleep, appetite changes and stronger cravings in the days before a period.

This does not mean autumn causes hormone imbalance. It means that the systems influencing reproductive hormones, stress hormones and sleep are connected. When one area is under pressure, symptoms may be more noticeable.

Support your body through the change

You do not need a complicated routine. Consistent habits give your body clearer signals.

Prioritise daylight early in the day. Spending time outdoors in the morning can support circadian timing and help reinforce the difference between day and night.

Eat regular, balanced meals. Include protein, fibre-rich carbohydrates and healthy fats to support steady energy and blood-sugar regulation. Skipping meals can make energy crashes and cravings more likely, especially during stressful periods.

Protect sleep consistency. Aim for a similar wake-up time each day where possible. Dim lights and reduce screen exposure before bed to support the body’s natural melatonin signal.

Review vitamin D. In countries with limited sunlight during autumn and winter, vitamin D intake is particularly relevant. Food sources include oily fish, eggs and fortified foods, while supplementation may be appropriate depending on individual needs.

Support key nutrients. Magnesium, vitamin B6, zinc and omega-3 fatty acids each have recognised roles in normal energy metabolism, nervous-system function and overall health. For women managing PMS symptoms, nutritional adequacy is a sensible place to start alongside sleep and stress support.

Your autumn reset

Feeling different in autumn is not a failure of discipline. It may be a sign that your body needs stronger daily cues: morning light, regular meals, movement, recovery and a consistent sleep routine.

If fatigue, low mood, anxiety, severe PMS symptoms, irregular cycles or sleep disruption are persistent or affecting daily life, speak to a GP or qualified healthcare professional.