Why would someone experience insomnia on guanfacine (Intuniv)?

From the Guidelines

Guanfacine can cause sleep disturbances, including insomnia, in some individuals due to its effects on the central nervous system, as evidenced by its common side effects of somnolence, fatigue, irritability, insomnia, and nightmares 1. This medication, which is commonly prescribed for ADHD and hypertension, works by stimulating alpha-2 adrenergic receptors in the brain, which can alter normal sleep patterns. Some people experience insomnia as a side effect, particularly during the initial weeks of treatment or after dose adjustments. The medication can disrupt the body's natural sleep-wake cycle by affecting norepinephrine activity in the brain. Other factors that might contribute to sleep difficulties include:

• The timing of doses (taking it too close to bedtime can be stimulating for some people)
• Individual sensitivity to the medication
• Interactions with other substances like caffeine or other medications If someone is experiencing sleep problems while taking guanfacine, they should not stop the medication abruptly but instead consult their healthcare provider, who might recommend adjusting the dosing schedule (often taking it earlier in the day), gradually reducing the dose, or switching to an alternative medication, as guanfacine has been shown to have a positive effect on functional impairment and quality of life in patients with ADHD 1. It is essential to weigh the benefits of guanfacine against its potential to cause sleep disturbances, considering the individual patient's needs and medical history, and to monitor its effects closely, especially when initiating or adjusting treatment, to minimize adverse effects and optimize treatment outcomes.

From the FDA Drug Label

Adverse reactions noted with guanfacine hydrochloride are similar to those of other drugs of the central α 2-adrenoreceptor agonist class: ... insomnia, In a second 12-week placebo-controlled combination therapy study ... the most commonly recorded reactions were: ... insomnia, 4%. Adverse reactions occurring in 3% or less of patients in the three controlled trials of guanfacine hydrochloride with a diuretic were: ... insomnia, In an open-label trial of one year's duration, 580 hypertensive subjects were given guanfacine, ... Adverse Reaction Incidence of adverse reactions at any time during the study n = 580 ... Insomnia 5% 0% There were 52 (8. 9%) dropouts due to adverse effects in this 1-year trial. The causes were: ... insomnia (n = 1), PSYCHIATRIC agitation, anxiety, confusion, depression, insomnia, nervousness

Someone may be unable to sleep on guanfacine because insomnia is a reported adverse reaction to the medication, occurring in 4% of patients in one study and 5% of patients in another study 2.

From the Research

Guanfacine and Sleep

• Guanfacine, a medication used to treat attention-deficit/hyperactivity disorder (ADHD), can lead to somnolence, which may affect a person's ability to sleep normally 3, 4.
• Studies have shown that guanfacine can cause a reduction in total sleep time, increased time awake after sleep onset, and decreased rapid eye movement (REM) sleep time 5.
• The exact mechanisms of how guanfacine affects sleep are not fully understood, but it is thought to be related to its action as a selective α2A-adrenergic receptor agonist 6.

Factors Contributing to Sleep Disturbances

• Somnolence is a common side effect of guanfacine, affecting up to 38.6% of patients, and can contribute to sleep disturbances 4.
• The timing of guanfacine administration, such as morning administration, may also affect sleep patterns 5.
• Concomitant use of other ADHD medications, such as methylphenidate or atomoxetine, may decrease the risk of sleep disturbances caused by guanfacine 3.

Clinical Implications

• Guanfacine's impact on sleep should be considered when prescribing the medication for ADHD treatment 3, 4.
• Patients experiencing sleep disturbances while taking guanfacine may need to adjust their medication regimen or explore alternative treatment options 7.
• Further research is needed to fully understand the effects of guanfacine on sleep and to develop effective strategies for managing sleep disturbances in patients taking this medication 4, 7.