[katieHaylor (OP)]

David asks:

After a couple of years of random headaches that started at the age of 54 I discovered that they were caused by fluctuations in my caffeine intake from tea and coffee. I must drink 8 or 9 mugs a day. I decided that it was better to go decaf rather than try to drink the same amount of caffeine every day.  If I accidentally drink a caffeinated tea or coffee I get a headache about 48 hours later even though I read that caffeine is metabolised in 4 to 6 hours. Do you know why this is?

Can you help?

[smart]

I get a headache about 48 hours later even though I read that caffeine is metabolised in 4 to 6 hours. Do you know why this is?

Read this: https://www.sciencedaily.com/releases/2009/05/090501162805.htm