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Attention Deficit Hyperactivity Disorder, otherwise known aws ADHD, is a complex condition. The inability to pay sustained attention to things can really cause problems when you're trying to go about your day to day.

But it's not just focusing that's an issue. It's really common for those with ADHD to have trouble sleeping, too. And that's actually created a chicken-and-egg question among researchers.

Does ADHD lead to sleep problems in some people, or do sleep problems lead to ADHD symptoms? Or a bit of both? The relationship between ADHD and sleep has been a feature of ADHD research for years.

Scientists and doctors have long received complaints from patients that they are just not able to get to sleep at the right time. And research has backed this up. For example, a study from 2008 found that up to 70% of kids with an ADHD diagnosis have issues falling and staying asleep.

That's a way bigger chunk than in the general population. And in adults with ADHD, studies have shown that 78% have delayed circadian rhythm -- something that happens in just 20% of the population without ADHD. Circadian rhythms are the hormonal cycles that keep our body clock in tune with the natural cycle of night and day.

And if this rhythm is delayed, it means that events that would happen at a certain time of day -- like getting sleepy -- start to happen later on. That means that many adults with ADHD are falling asleep later, and sleeping for shorter amounts of time. As anyone that's ever pulled an all-nighter can tell you, a night without enough sleep can make things a whole lot harder the next day.

A 2008 study showed that in kids with ADHD, moderate to severe sleep issues were associated with poorer outcomes, as well as causing problems for their family's day-to-day -- like getting to work and school on time. It's not always just falling asleep late, either. Many of those with ADHD also experience sleep disorders, such as sleep apnea or restless leg syndrome, which interrupt and reduce the quality of sleep that they do get.

And, especially in kids, this can cause some behavioral issues. Some might be sleepy during the day, but sleep deprived children are especially prone to acting hyperactive and impulsive, or have trouble focusing, when they're tired out. And some researchers suggest that even in adults with ADHD, hyperactivity is a strategy the brain might use to try keep itself awake.

Thus our chicken-and-egg question:. Is it ADHD that's causing these sleep issues, or could those sleep issues be causing ADHD symptoms? Well, as with many things in psychology, so far there's no consensus.

The most likely explanation seems to be that ADHD and sleep interact with each other as bilateral comorbidities. That means they may share a common underlying cause, with symptoms of one exacerbating symptoms of the other. A 2010 study of adults with ADHD looked at the symptoms and sleep patterns of forty [40] patients.

The researchers found that the presence of sleep onset insomnia -- that delay in falling asleep -- was more present in those who had ADHD with hyperactivity, as opposed to those who were primarily inattentive. This suggests that there may be some weight to the idea that hyperactivity is, at least in some people, the result of poor sleep. But it's not as simple as just going to bed later.

In another study from 2013, researchers measured levels of melatonin -- a hormone that regulates our circadian rhythm -- throughout the day. They found that the circadian rhythms of those with ADHD was delayed by about a 105 minutes, compared to non-ADHD controls. That means that they aren't getting that same melatonin-induced sleepiness when daylight started to dim.

Instead, they were feeling it almost two hours later, pushing back their whole sleep cycle. These researchers have said the next step is to figure out why that is. It may be that at least some people with ADHD may be insensitive to melatonin, or maybe even that the receptors in their eyes designed to pick up changes in light may be working atypically.

Fortunately, there are treatment options. And therapies that help correct circadian rhythms have already been shown to be effective in addressing symptoms of ADHD. A long-term study of 101 children with ADHD and sleep onset insomnia looked at the effect taking melatonin supplements had on both their symptoms of ADHD and their sleep patterns.

After participating in a randomized control trial, the participants were contacted about three and a half years down the line to see whether melatonin was still proving helpful for them. They found that 65% of the children still used melatonin daily, and that in 88% of cases, it was effective in inducing and maintaining better sleep. 71% reported improvements in behavior, while 61% also saw improvements to their mood. What's more, this study found that 92% of those who stopped taking melatonin saw their delayed sleep onset come back.

Which adds even more weight to the idea that there's something biologically predisposing those with ADHD towards this altered circadian rhythm. As we mentioned up top, ADHD is a really complex condition, and there are other theories as to what might be going on, and even other approaches to correcting these kind of sleep patterns beyond just taking melatonin. But research like this shows us that sometimes it's not always a simple case of cause and effect, and that different cognitive and biological functions can play off each other, both for better and for worse.

We hope you've enjoyed this episode of SciShow Psych, and maybe even learned why you're watching it at 3 am. All our SciShow channels are made possible by the support of our generous, amazing patrons. If you want to join our community of awesome humans, and get access to neat perks like bloopers and our patron-only Discord, check out patreon.com/scishow. [ outro ].