Before menstruation, some women may experience drowsiness and weakness, but it is not specific and cannot be taken as a direct sign of menstruation. There are many reasons for drowsiness and weakness in women, which should be highly alerted. In the late luteal phase before menstruation, the female organism may show some obvious symptoms due to the withdrawal of estrogen and progesterone, such as drowsiness, weakness, headache, back pain, breast pain, abdominal distension, edema, weight gain, loss of motor coordination, emotional instability, easy fatigue, and increased or decreased appetite. Most commonly seen in women aged 25-45 years, it usually appears 1-2 weeks before menstruation and can rapidly decrease until it disappears after the onset of menstruation. Drowsiness can also be caused by other reasons, such as sleep disorders, hypothyroidism, anemia, etc. Therefore, you should not assume that menstruation is imminent just because of drowsiness and weakness. If drowsiness and weakness occur for a long time but are not related to the menstrual cycle, patients need to go to endocrinology and general medicine departments for examination to clarify the cause.