After a knock to the head or a hard stop in a car, most people write down the headache, the neck, or the dizziness. Fewer people write down the changes they notice in themselves at home. You snap at a question you would normally answer kindly. A song you like sets you off. You want to be alone at a time you usually want company. These shifts are easy to dismiss as a bad day, and sometimes that is all they are. A written record helps you tell the difference between one bad day and a pattern.
This note is for education, not diagnosis. It cannot tell you what a change means. It gives you a way to bring a clear account to a clinician, who can decide what to make of it.
Start with a plain baseline
Before you write anything about this week, think about the month before the event. Were you generally patient? Did you handle noise, traffic, or a crowded store the usual way? Write two or three sentences in ordinary words. A baseline keeps you from judging every change against a memory that has been smoothed over by time.
If you cannot remember much about your usual mood, ask someone who knows you well. Write down what they describe, along with their name and how they know you. Do not fill in gaps for them, and do not guess.
Write one line each day
Each evening, write one line with four parts: the date, what happened, how you reacted, and how long the reaction lasted. For example: the date, a slow cashier, you felt short with them, it passed within ten minutes. Keep the words flat. Irritable is a fine word. A longer description is fine too, as long as it stays with what you did and felt.
Add a note about the body if it fits. Did a headache come before the short temper? Was the room loud? Had you skipped a meal or slept badly? You are not trying to find a cause. You are listing what was going on so the pattern has context around it.
Notice the kinds of change
Mood changes after a head injury can show up in several ways. Some people become quicker to anger. Some become tearful over small things. Others go flat and lose interest in things they used to enjoy. Some find they cannot stay around people for long stretches. Write down which kind fits you, using your own words.
Also note how it affects the people around you. Did someone ask you to slow down, or did you pull back from a plan you had made? These details matter to a clinician, and they are easy to forget a few weeks later. Writing them down the same day keeps them accurate.
Look for the change over time
Read your log every few days. Are the hard moments getting shorter, or staying the same? Do they cluster at certain times, such as late afternoon or after a long drive? A pattern that holds steady or grows is worth describing at a visit. So is a change that arrives suddenly and does not match anything in your usual routine.
Pay attention to safety. If mood changes come with confusion, a sharp shift in behavior, trouble with basic tasks, or thoughts of harming yourself or someone else, do not wait for a scheduled appointment. Contact a medical professional or emergency services right away.
Bring the log to your visit
Bring the written log, your baseline note, and a short list of questions. Ask what the clinician sees as the most useful next step, and whether your mood changes should be looked at by another member of your care team. Keep your own copy of the log. Ask the clinic how they prefer to receive it, and keep the original with you.
If you are in the St. Louis metro and deciding whether to get examined this week, a short log can make that first call easier. You will know what to say, what to leave out, and what to ask. Keep it simple. Ten lines a week will tell you more than a long diary you stop writing by day four.