If your teenage son or daughter starts having mood swings, and stays out late, then it could very well be a sign that your kid is in love.
The finding is based on a new research by Swiss researchers at the Psychiatric University Clinics Basel, who conducted it on 107 adolescents with an average age of 17.98 years.
Out of the total participants, 60 had indicated that they were in love, and were experiencing intense romantic love, while the rest 47 were in a longer-lasting relationship or were single.
The participants were asked to complete questionnaires related to hypomania and sleep habits, and maintain a sleep log for seven consecutive nights, reports the Telegraph.
The researchers found that teens in the early-stage intense romantic love were more prone to mood swings, both in the morning and evening, as well as getting less sleep, less daytime sleepiness, and heightened concentration during the day.
The researchers noted that physiological changes amongst the teens in the early stage of romantic love included sweaty palms, pounding hearts, and increased and excessive energy when they were around their beloved.
On an emotional level, changes included obsessive, intrusive and persistent thinking about that person, and emotional dependency on and craving for emotional union with him or her.
The researchers also found that teens in love also showed extreme empathy and distorted altruism, which meant that they were "willing to die for" their beloved.