Winter fatigue, often dismissed as seasonal sluggishness, could indicate low haemoglobin levels, also known as anaemia. While shorter days and cold weather naturally reduce energy, persistent symptoms like breathlessness, dizziness, or unusual weakness may signal a health issue. Haemoglobin's role in oxygen transport means low levels can cause constant tiredness, headaches, and rapid heartbeat. Winter can exacerbate these symptoms due to factors like reduced vitamin D and increased consumption of iron-poor comfort foods.