Modafinil is usually taken in the morning for narcolepsy or excessive sleepiness associated with obstructive sleep apnoea (OSA). The harder question is what happens when the dose is taken later and bedtime is approaching. Because modafinil is cleared slowly, later dosing can leave more of the drug in the body during the intended sleep period….

Modafinil generally reaches its peak plasma concentration 2 to 4 hours after an oral dose. This refers to the highest measured concentration of modafinil in plasma, not necessarily the point when its effects feel strongest. Key Takeaways What Does “Peak” Mean for Modafinil? When researchers describe a drug as reaching its peak, they are usually…

Modafinil can reduce rapid eye movement (REM) sleep under some conditions, particularly when higher doses are taken close to the intended sleep period. However, human sleep studies do not show that modafinil consistently or selectively suppresses REM sleep. In the clearest direct experiment, Turner et al. (2014) found that higher doses reduced both total sleep…

Yes. Irritability can occur with modafinil, although larger controlled safety studies more consistently report nervousness, anxiety and insomnia.[1,2] Direct evidence for irritability comes from a small controlled study in healthy volunteers, while high-dose clinical experience and psychiatric case reports provide additional evidence that mood and behavioural changes can occur.[1,3,4] Key Takeaways Is Irritability a Common…

Some people describe feeling unusually tired or sleepy as modafinil’s effects become less noticeable. That experience is often called a “modafinil crash,” but the term can refer to several different things. Late-day sleepiness, return of an underlying sleep disorder, accumulated sleep pressure, and rebound sleepiness are all possible explanations. These are not necessarily the same…

Modafinil is sometimes associated with symptoms such as dry mouth, raising the question of whether it also causes dehydration. The available human evidence is limited, but studies examining water turnover, sweating, and heat regulation provide some useful clues. Key Takeaways Does Modafinil Actually Dehydrate You? The most directly relevant evidence comes from Cuddy et al….

Modafinil and tadalafil have not been directly tested together in a clinical drug-interaction study. However, human pharmacokinetic research suggests that regular modafinil use could reduce tadalafil exposure because modafinil can increase CYP3A4 activity, an enzyme pathway involved in tadalafil metabolism. How large that effect might be with modafinil specifically is not known. Key Takeaways Do…

Modafinil is meant to keep you awake. Zaleplon is meant to help you fall asleep. That makes zaleplon an obvious drug to wonder about if modafinil is still keeping you awake when you need to sleep. There is some evidence connecting the two drugs, but not as much as the question might suggest. A patent…