How Long Does Mydayis Last? Onset, Duration and Sleep
What the Mydayis label says about when it starts, why it can last up to 16 hours, how food moves the peak and why insomnia is common, plus what to log.
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Disclaimer: This article is for education only. It is not medical advice, a diagnosis, or a dose recommendation. Only your prescriber can decide whether your dose, timing or medication should change. Never change how you take a medicine without talking to them first.
What Mydayis is
Mydayis is a once-a-day amphetamine capsule approved in the US for ADHD in people aged 13 and older [1]. It contains the same four amphetamine salts as Adderall XR [1][2], but each capsule holds three types of beads. One type releases straight away, and the other two are delayed-release beads, one that releases at pH 5.5 and one at pH 7.0 [1]. The point of that design is a longer day of coverage from a single morning dose.
The longer day is also why sleep comes up so often with Mydayis. This guide goes through what the US label says about how long a Mydayis day lasts and what that means for sleep, and then what is worth logging for your prescriber. All figures come from the FDA prescribing information on DailyMed. They are study averages, not a prediction for you.
What the label says at a glance
| Question | What the Mydayis label says |
|---|---|
| When to take it | Once a day in the morning, as soon as you wake up [1] |
| How long it can last | Effects may last up to 16 hours [1] |
| When it started to help in studies | In adult studies, improvement over placebo was statistically significant from 2 hours after the dose in one study and from 4 hours in another, and stayed significant through 16 hours [1] |
| When blood levels peak | About 8 hours after the dose in adults, and about 7 to 10 hours in younger patients [1] |
| Half-life | About 10 to 11 hours for d-amphetamine and 10 to 13 hours for l-amphetamine [1] |
| Food | With or without food, but the same way each time. A high-fat meal did not change the total absorbed but pushed the peak from about 7 hours to 12 hours [1] |
| Missed dose | Don't take it later in the day, and don't take extra to make up for it [1] |
| Dose changes | The label describes changes no sooner than weekly, set by the prescriber [1] |
| Steady state | Reached between days 7 and 8 of daily dosing [1] |
How long Mydayis lasts
The label's figure of "up to 16 hours" comes from studies that tested attention with a timed math task at 2, 4, 8, 12, 14 and 16 hours after the dose [1]. In the two adult studies of this kind, Mydayis did better than placebo from either 2 or 4 hours after the dose all the way through 16 hours. A study in teenagers found the same window, from 2 to 16 hours [1].
The label also compares Mydayis with taking two separate doses. A single Mydayis capsule gave blood levels similar to an extended-release mixed amphetamine salts capsule followed by an immediate-release dose 8 hours later [1]. So one Mydayis capsule is built to cover roughly what some people would otherwise get from a morning capsule and an afternoon booster.
Mydayis isn't interchangeable with other amphetamine products milligram for milligram. The label says not to substitute it that way, because the amphetamine content and release profiles differ [1].
Mydayis and sleep
The label is direct about this. It tells people to take Mydayis when they wake up "because the effects of MYDAYIS may last up to 16 hours and there is potential for insomnia" [1]. If you wake at 7 a.m., 16 hours takes you to 11 p.m.
Insomnia was the most common side effect in adults. In three pooled adult studies, 31% of people on Mydayis reported insomnia compared with 8% on placebo, and those studies included doses above the usual maximum [1]. The label notes that insomnia generally showed up early in treatment [1]. In the teenage study, insomnia was reported by 8% on Mydayis and 3% on placebo [1]. About 2% of adults stopped treatment because of insomnia [1].
Food matters for sleep more than most people expect. After a high-fat meal, the peak arrived about 12 hours after the dose instead of about 7 [1]. A heavy breakfast doesn't change how much you absorb, but it moves the strongest part of the curve later into the evening. That is one reason the label asks people to take it the same way each day, either always with food or always without [1].
Children aged 12 and under had higher blood levels than teenagers at the same dose and higher rates of insomnia and reduced appetite, which is why Mydayis isn't approved for that age group [1].
The ADHD and sleep guide covers how stimulants affect sleep more generally and what to note about bedtimes.
Taking it and what to avoid
The capsule can be swallowed whole, or opened and the whole contents sprinkled over a spoonful of applesauce. The applesauce should be eaten straight away without chewing, and a single capsule's dose shouldn't be split [1]. Opening the capsule onto applesauce gave absorption comparable to swallowing it whole [1].
The label advises avoiding alcohol while taking Mydayis, because alcohol may make the capsule release its dose faster [1].
What to log and show your prescriber
With a medicine that can run until bedtime, what your prescriber most wants to see is how long your day on it really is and what it does to your night. A few lines a day will show that.
| What to log | Why it helps |
|---|---|
| The time you took it and the time you woke up | The label ties the dose to waking, so the gap matters |
| Breakfast, roughly (nothing, light, heavy) | A high-fat meal moved the peak about 5 hours later in the label study |
| When you noticed it start and when it faded | Shows your own window against the label's 2 to 16 hours |
| A focus or "how the day went" score, 1 to 5 | Lets you compare days |
| Bedtime, how long it took to fall asleep and how you slept | Insomnia was the most common side effect in adults |
| Appetite and when you ate | Decreased appetite was also common |
| Side effects such as anxiety, a racing heart or irritability | Helps your prescriber judge tolerability |
Bring a summary to your review, such as "on heavy-breakfast days I couldn't fall asleep before midnight." Notes like that are easy for a prescriber to act on. Titrate logs dose times, check-ins and sleep with one tap and builds a dated report, so you have the pattern in front of you. If you are comparing Mydayis with another stimulant, the switching stimulants report template has a layout for that.
Don't change your dose, its timing or how you take it based on what you find. Share it, and let your prescriber decide.
If you have chest pain, a racing or pounding heart that doesn't settle, fainting, severe agitation, hallucinations or thoughts of self-harm, contact your doctor or urgent care right away.
Key takeaways
- Mydayis is a once-daily amphetamine capsule with three types of beads, approved for people aged 13 and older.
- The label says effects may last up to 16 hours, and studies found improvement over placebo from 2 or 4 hours through 16 hours.
- Because of that length, the label says to take it on waking and not later in the day, even after a missed dose.
- Insomnia was the most common adult side effect, at 31% compared with 8% on placebo, and it tended to appear early in treatment.
- A high-fat meal moved the peak from about 7 to 12 hours, so log breakfast and sleep together and bring the pattern to your prescriber.
FAQ
Q: How long does Mydayis last? The label says its effects may last up to 16 hours. In attention studies, adults did better than on placebo from 2 or 4 hours after the dose through 16 hours, and teenagers from 2 to 16 hours. How long it lasts for you is worth logging, because your own window may be shorter or longer.
Q: How long does Mydayis take to kick in? The label doesn't give a single onset time. In the adult attention studies, improvement over placebo was first statistically significant at 2 hours in one study and 4 hours in another. Blood levels peak about 8 hours after the dose in adults.
Q: Why can't I sleep on Mydayis? The label says the effects may last up to 16 hours and that there is potential for insomnia, which is why it should be taken on waking. Insomnia was reported by 31% of adults in studies compared with 8% on placebo. Log your dose time, breakfast and bedtime, and talk to your prescriber rather than changing anything yourself.
Q: Can I take Mydayis later if I forget my morning dose? The label says not to take a missed dose later in the day and not to take extra to make up for it. The next dose is taken the following morning at the usual time. If you often miss doses, mention it to your prescriber.
Q: Does food affect Mydayis? A high-fat meal did not change how much was absorbed, but it delayed the peak from about 7 hours to 12 hours. The label says Mydayis can be taken with or without food but asks people to take it the same way each time.
Q: Is Mydayis the same as Adderall XR? They contain the same four amphetamine salts, but Mydayis has three types of beads and is built to last longer. The label says a single Mydayis capsule gave blood levels similar to an extended-release mixed amphetamine salts capsule plus an immediate-release dose 8 hours later. It also says not to swap it for other amphetamine products milligram for milligram.
References
- FDA prescribing information — Mydayis (mixed salts of a single-entity amphetamine) extended-release capsules, sections 1, 2, 6, 8.4, 11, 12.3, 14 and 17, DailyMed
- FDA prescribing information — Adderall XR (mixed amphetamine salts) extended-release capsules, product description, DailyMed
This article is for educational purposes only. It does not constitute medical advice. Always consult your licensed healthcare provider about medication decisions.