Introduction and objective:
Nomophobia (NMP) is a present-age phobia of loss of use of information and communication technologies (ICT), particularly smartphones.

Material and methods:
The study adopted a two-phase, exploratory consequential mixed methods design. The first phase was a quantitative exploration of the degree of NMP. The second mapped the potential area of risks in using modern ICT. Three working hypotheses were established to compare the opinions of secondary school students, their behaviour and degree of NMP. A 20-item anonymous questionnaire was administered to 373 boys and girls aged 14–15 in 11 randomly-selected secondary schools in the Czech Republic.

Results:
The results prove that 0.5% of the subjects did not exhibit symptoms of NMP, a very mild form of NMP was detected in 71% of respondents, a mild form of NMP was detected in 18.7% of the respondents, a moderate form of NMP was detected in 7.8% of respondents, and a severe form of NMP was detected in 2% of respondents. Almost three-quarters of the students were not directly at risk of dependence on a mobile phone, but a 10th of the sample exhibited a set of symptoms of behavioural addiction. On average, respondents used 4 applications, communication programmes, social networks, and music players. Girls reported a higher dependence on mobile phones in comparison to boys.

Conclusions:
Further investigations should directly ascertain which integrands predict NMP, identifying risk groups, and developing preventive strategies (social and environmental factors) to better understand the underlying cause of NMP.