Influence of methylphenidate on circadian rhythmicity and sleep in adult attention-deficit/hyperactivity disorder

To explore the effect of methylphenidate on sleep and circadian rhythmicity, actigraphic sleep-wake rhythm, Dim Light Melatonin Onset (DLMO), Phase Angle Difference (PAD; time between DLMO and mid-sleep) and attention-deficit/hyperactivity disorder (ADHD) Rating Scale were assessed before and after 4-week treatment with methylphenidate in 10 adults with ADHD. During methylphenidate treatment DLMO did not change, while melatonin concentration at 23.00 hours increased. Phase advance type (PAD > 6 h) before treatment was associated with a greater treatment-related reduction in attention symptoms. These results suggest that PAD > 6 h might have a predictive value for the effect of methylphenidate.