b in the form of a transdermal patch such a kit is exemplified by way of illustration only by a kit comprising the melatonin containing tablets and the nicotine containing patch described in formulation examples a and b below in accordance with the present invention it was unexpectedly found that while melatonin levels in smokers and non smokers were comparable administration of melatonin controlled release 2 mg daily in the evening for 4 weeks had a significantly greater effect on the improvement of sleep quality in smoking than non smoking patients with insomnia aged 55 years and older over the values found with placebo treatment of the same individuals e g as shown in example 1 in addition administration of melatonin controlled release 2 mg daily in the evening for 3 weeks had a significantly greater effect in smoking than non smoking patients with insomnia aged 20 55 years in the improvement of sleep quality e g as shown in example 2 moreover administration of melatonin controlled release 2 mg daily in the evening for 3 weeks had a significantly greater effect in smoking than non smoking patients with insomnia aged 55 years and over with respect to the enhancement of psychomotor skills e g as shown in example 3 even more surprising was the finding that a single administration of melatonin controlled release 2 mg resulted in a significantly improved memory recall over that under placebo treatment in the same subjects who were smokers or ceased smoking less then 6 months before the trial compared to that in non smokers e g as shown in example 4 the invention will now be illustrated by the following non limiting examples the effect of a controlled release formulation of melatonin on subjectively assessed sleep quality in.