A retrospective analysis of 62 children and adolescents treated with clonidine for sleep disturbances associated with ADHD is reported from the outpatient Pediatric Psychopharmacology unit, Massachusetts General Hospital, Boston. Using the National Institute of Mental Health global assessment of sleep improvement, 85% of patients treated with nighttime clonidine (50-800 meg, mean 157) for 35 months were much to very much improved. Concurrent pharmacotherapy and comorbidity showed no relation to response. Mild adverse effects in 31% included morning sedation and fatigue. 
COMMENT. Two thirds of the patients had medication-induced ADHD-associated sleep disturbance, mainly stimulants. The addition of clonidine in combination with stimulants such as methylphenidate in this study appeared to be safe and effective in correcting sleep disturbances. Fatalities have been reported using clonidine and methylphenidate together, and this combination therapy is being discouraged. The authors recommend further systematic assessment in large groups of children to clarify this issue. Clonidine is indicated in the treatment of ADHD, tic disorders, and comorbid ADHD and tic disorders. Somnolence, the most common side-effect of clonidine, often reduces its usefulness.
Pharmacotherapy of ADHD is reviewed in a special article from the Massachusetts General Hospital . The efficacy of stimulants in 70% of subjects has been documented in 155 controlled studies of 5,768 children, adolescents, and adults reported in the literature. Stimulants improve abnormal behaviors in ADHD, self-esteem, cognition, and social and family function. Response varied with age and comorbid conditions. The efficacy of tricyclic antidepressants in ADHD is also documented in more than 1000 subjects. Increased interest in comorbidity in ADHD has not been followed by related therapeutic advances. Data are limited on the response of medications in comorbid ADHD, and on the effects and safety of combined pharmacotherapy.
One of my readers has reminded me of studies carried out in the 1970s regarding the effect of pyridoxine hydrochloride on hyperactive children having low levels of whole blood serotonin. Colleagues interested in revisiting the use of vitamin B6 in ADHD are referred to studies by Coleman M, Coursin DB et al. Pediatrics 1975;55; Monogr neural Sci 1976;3:133-136; Biol Psychiatry 1979;14:741. Pyridoxine-induced sensory neuropathy has occurred with doses as low as 50 mg/day when continued for months or years, and megadoses for the treatment of ADHD must be employed with caution. (see Ped Neur Briefs Feb 1995;9:14).