Researchers wanted to see if there was any correlation between when we worry most about our health and weekly patterns in sickness.
For example, numerous studies suggest heart attack rates spike on a Monday.
A 10-year study in Scotland revealed cardiac deaths peak then before hitting a low on Tuesday.
Weekend binge-drinking, coupled with the stress of going back to work, is thought to put the heart under added strain.
Other studies meanwhile, suggest Wednesday is the gloomiest day of the week - possibly because it is the furthest point from the weekend.
The San Diego team analysed internet searches on Google for health on every day between 2005 and 2012.
They broke it down as a percentage of overall search volume and found that Monday and Tuesday queries were 30 per cent greater than the rest of the week combined.
Searches dropped by three per cent on Wednesdays, 15 per cent on Thursdays, almost half on Fridays and by a whopping 80 per cent on Saturdays.
On Sundays, interest in health bounced back slightly - before peaking again on Mondays.
In a report on their findings the researchers said the results tally with evidence that blood pressure, heart attacks, strokes and infectious diseases all seem to peak early in the week - a health pattern known as circaseptan rhythms.
They said one explanation is that Monday is "akin to a mini New Year's day", where the excesses of the weekend result in a demand for health information.
"Poor health choices during the weekend may promote a desire to cleanse come Monday.
"There is strong potential for improving public health.
"Health promotion campaigns could immediately be made more cost effective by targeting the population early in the week rather than uniformly across the week."
- Daily Mail