One-in-ten Britons use sunbeds each year despite it increasing the risk of skin cancer - including melanoma, the deadliest form of the disease.
Now a simple new tool has found up to a fifth are at risk of getting hooked on the practice
The Behavioral Addiction Indoor Tanning Screener (BAITS) is a survey including seven questions.
Among 330 current users of sunbeds 19.7 per cent tested positive for symptoms of a potential indoor tanning addiction.
This compared to 1.8 per cent of 553 former users who had not used one in the last 12 months.
Dr Katharina Diehl, of Heidelberg University in Germany, said: "BAITS can be used as a screening tool in large surveys.
"But it may also help physicians and health care providers to identify individuals in particular need of specific counselling to avoid the continuous use of tanning beds.
"By this psychological testing of the BAITS it will be proven how accurate it is in identifying indoor tanning addicted individuals."
The technique was developed based on a model of addiction disorder designed to capture the main features of the behaviours.
This includes diminished control and temptations that lead to urges or cravings.
Ultraviolet (UV) radiation from sunbeds has been classified as carcinogenic to humans.
A growing body of research suggests excessive tanning is a behaviour with the potential to become addictive.
The study published in the British Journal of Dermatology used data from the National Cancer Aid Monitoring on Sunbed Use (NCAM) which includes a cognitive pretest and a survey of 3,000 German individuals.
Dr Diehl said BAITS is not a final diagnosis of indoor tanning addiction - which would require a more formal assessment - but does identify potential symptoms
Nina Goad, of the British Association of Dermatologists, said: "This is an interesting pilot study with two important developments.
"The first is a new way of measuring symptoms of tanning addiction in a large population group.
"The second is the finding - on testing this method - that as many as one in five sunbed users may have symptoms of addiction.
"There is strong evidence use of sunbeds increases the risk of skin cancers including malignant melanoma which is the most deadly type.
"For people who start using sunbeds before the age of 35 years the relative risk of malignant melanoma almost doubles.
"If indoor tanning does indeed have addiction potential, being able to assess the scale of the problem will be imperative.
"It certainly would help to explain why so many people continue to use sunbeds despite knowing the risks."
Skin cancer risk
Skin cancer is the most common cancer in the UK. At least 100,000 new cases are diagnosed each year - and the disease kills over 2,500 people annually.
The cost to the NHS of treating non-melanoma skin cancer is expected to rise to £465m a year by 2025 as a direct result of people getting tans on foreign holidays and in salons.
Cancer Research UK says the UV rays from sunbeds can damage the DNA in skin cells. Over time this can build up to cause skin cancer.
It says: "Sunbeds can sometimes be marketed as a 'controlled way' of getting a 'safer tan'. But actually, sunbeds are no safer than exposure to the sun itself.
"And using a sunbed before you go on holiday doesn't protect against further damage from the sun while you're away."
Mediterranean midday sun
One study found the average skin cancer risk from sunbeds can be more than double that of spending the same length of time in the Mediterranean midday summer sun.
The charity says: "IARC (International Agency for Research on Cancer) agrees there is sufficient evidence to show using sunbeds causes melanoma skin cancer, the most serious form.
"They also state that sunbeds provide no positive health benefits.
"Combining the results of studies on sunbeds and cancer shows that using a sunbed increases melanoma risk by 16 to 20 per cent."