There are many causes of headache. If you wake up with headache on the left side, but it is not accompanied by symptoms of neurological deficits such as unfavorable limb movement and clumsy speech. Consider that it may be caused by poor rest or improper sleep posture. In this case, you can give the patient symptomatic pain medication to relieve the headache, and you can take oral medication such as aminoglutethimide tablets, ibuprofen extended-release capsules, pain relief tablets, and indomethacin to relieve the headache. If it is caused by elevated blood pressure, you can take oral antihypertensive drugs to lower the blood pressure to relieve the left side of the headache. If the headache is caused by poor sleep or staying up late in the morning, the patient should rest more, and the headache can be relieved after rest.