The link among melatonin levels, pineal function, insomnia and affective spectrum is strengthened by epidemiologic and chronobiological evidence. From the affective spectrum, we selected the hyperthymic temperament, which is characterized by exuberant, upbeat, overenergetic, and overconfident lifelong traits.

We examined whether insomnia in persons with hyperthymic temperament responds particularly to the treatment with melatonin, in comparison with the euthymics patients with insomnia.

We ran an open label study on 20 subjects. None suffered from depression, mania or hypomania.

The study population comprised two groups: one group with patients with insomnia whose temperament presented hyperthymic traits (10 subjects) and the other group with euthymic adults, (10 subjects).

The Athens Insomnia Scale 5-item version (AIS-5) was administered to the two groups before and after the treatment with melatonin. The AIS is a self-assessment psychometric instrument designed for quantifying sleep difficulty based on the ICD-10 criteria.The patients took a single daily dose of 5 mg of melatonin with 30 minutes before bedtime. Using the AIS-5, we have assessed sleep at baseline and after 4 weeks of treatment. SPSS version 11 was used for statistical analysis.

After 4 weeks of melatonin therapy (5 mg/day), the comparison of the two groups showed that melatonin is more effective in the insomniacs with hyperthymic temperament comparative with the euthymic patients.

Melatonin has shown promising results in the treatment of insomnia in patients with hypertimic temperament. Further studies are necessary to better investigate the role of melatonin on insomnia in bipolar spectrum.