Other white lies to make the top five included "I've got to get up early in the morning" and "I'm pre-occupied with work". The conclusion was made after studying 4,000 adults.
The not-so-kinky research also revealed that one in five Brits regularly make excuses to avoid having sex.
Seven out of 10 said they were often too exhausted to enjoy sex. And four out of 10 said the recession had played havoc with their sex life, the study found, reports The Telegraph.
A spokesman for www.OnePoll.com, which carried out the study, said: "The humble headache has had its day as far as excuses are concerned.
"Tiredness plays a much bigger part in our reasons not to climb between the sheets these days and enjoy some quality time together.
"And its hardly surprising when we are all working longer hours than ever before and have so many things to worry about.
"Fears over whether will be able to pay our mortgages or even whether we will have a job in a month's time are bound to affect our bedroom performance.
"It was intriguing to see just how the recession has affected our passion levels too."
The report also found men are more likely to make excuses than women with 27 per cent admitting they often avoided sex compared to 18 per cent of women.
Top Ten Sex Excuses
1. Too tired
2. I'm not in the mood
3. I've got a headache
4. I've got to get up in the morning
5. I'm pre-occupied with work
6. I'm angry with you
7. I can hear one of the children
8. You need a shower
9. I've got a bad back
10. Too soon in our relationship.