Also in this week's column:

• Can you die from testing a 9V battery on your tongue?
• What issues are there for women in space?
• Why do babies always seem to have a runny nose?

Why doesn't a hangover occur the night before?

Asked by Anna Ro of Newtown, New South Wales, Australia

This type of headache is technically called a "delayed alcohol-induced headache" or DAI headache.

According to the Mayo Clinic in Rochester, Minnesota, symptoms of a DAI headache include "a pulsating pain that's felt in front and on both sides of your head. It may worsen when you move around".

A DAI headache from excessive drinking is due to the following:

• Alcohol contains the chemical ethanol.
• Ethanol causes blood vessels to expand.
• Such an expansion can give you a headache.
• Ethanol also disrupts the body's water balance and causes dehydration. Dehydration contributes to headaches.
• Congeners are flavouring ingredients frequently added to various alcoholic beverages, particularly the darker colored ones. Congeners also can cause headaches. Congeners in high amounts can even be toxic.
• When alcohol is metabolised by the body, the blood becomes more acidic than normal. This is called acidosis. It too can contribute to a headache.

Alcohol ingestion can alter the normal daily rhythm of various body functions. After the assault upon the body from too much alcohol occurs, it takes time for the body to respond to the stress and eventually get back to normal. Thus a hangover is not immediate.

And just because you may have a headache that's DAI doesn’t mean you should risk a DUI.

Stephen Juan, Ph.D. is an anthropologist at the University of Sydney. Email your Odd Body questions to s.juan@edfac.usyd.edu.au