Sleeping pills can leave you with ‘morning-after brain’ – here’s why you feel groggy the next day

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How common is insomnia – and how many people use sleeping aids?

Insomnia is a huge problem, affecting around 10 per cent of adults worldwide, according to sleep studies. So it’s no surprise that many people turn to sleeping pills when they’re struggling to get a good night’s sleep.

While there’s no concrete figure for how many people in the UK regularly rely on sleeping tablets, 2024 figures from a US study revealed that almost one in eight American adults now use a sleep aid most days or every day.

As someone who has occasionally taken a small dose of zopiclone – a prescription sleeping tablet that belongs to a group of medicines called hypnotics – I know how they can contribute to a good night’s sleep when you’re absolutely desperate.

And while I don’t have figures for how many people in the UK take zopiclone, a report published in 2024 found there were 4.31 million prescription items for the drug, down around 4 per cent from 4.49 million in 2023.

Why can sleeping pills affect your brain the next morning?

Sleeping tablets work by reducing activity in the brain to help you sleep. But for some people, that effect doesn’t disappear the moment they wake up.

The NHS specifically lists feeling tired, sleepy, dazed or less alert the following day as common side effects of zopiclone.

According to Dr Ahmed Shoka, a consultant psychiatrist at Medical Express Clinic sleeping tablets can remain active in the body for several hours after they have helped you fall asleep.

“Most of the common ones, including drugs like zopiclone and older benzodiazepines, stay in your system for hours after they’ve done their job of getting you to sleep. That’s where the ‘morning after brain’ comes from: you’re technically awake, but part of your brain is still catching up,” he explained.

Memory can be affected

One of the most noticeable effects can be problems with memory and concentration.

“These drugs work by damping down brain activity, and that includes the parts that lay down new memories,” Dr Shoka said.

“People often describe a foggy patch: they’ve had breakfast, replied to messages, even had a conversation, but can’t recall it clearly a few hours later.”

Sleep consultant Maryanne Taylor, who works at The Sleep Works points out that insomnia itself can also cause poor concentration, low mood, irritability and brain fog.

That means there can be a difficult balance between getting much-needed sleep and experiencing side effects from the medication.

“If a sleeping tablet helps someone sleep and they do not experience significant next day effects, they may feel clearer, calmer and better able to function,” she explained.

“However, because some sleeping tablets can leave people feeling groggy, dazed or mentally slower the next morning, it’s a fine balance to decide what’s best for you.”

Why you might feel groggy the next day

The effects can go beyond feeling a little tired.

Dr Daniel Atkinson, clinical lead at Treated says some over-the-counter sleep aids can also cause drowsiness the following day.

“These include herbal options, which contain ingredients like valerian root extract, and tablets like promethazine and diphenhydramine hydrochloride, which are antihistamine medications that also cause drowsiness,” he explained.

“Medications like diphenhydramine hydrochloride list sedation, drowsiness, dizziness and unsteadiness among the common side effects they can cause.”

How strongly someone experiences these effects can vary. Factors such as when the medication was taken, whether alcohol was consumed, individual metabolism and how many hours of sleep someone gets can all play a role.

Can sleeping pills affect your mood?

For some people, the morning-after effects aren’t just physical.

Dr Shoka says people can wake feeling “flat, irritable, or oddly detached” rather than refreshed.

He also says some people may experience a return of anxiety once the effects of the medication wear off, although individual reactions vary.

“If you’re relying on them regularly, or noticing memory lapses or low mood most mornings, you should speak to your GP about what’s actually driving the poor sleep, rather than treating the tablet as the long-term fix,” he said.

What about over-the-counter sleeping tablets?

Prescription medicines such as zopiclone aren’t the only sleep aids that can cause next-day effects.

Some over-the-counter products contain antihistamines such as diphenhydramine or promethazine, while others contain herbal ingredients such as valerian.

Dr Atkinson says most over-the-counter sleep aids are intended for short-term use.

“You can build up a tolerance to them, which means they may become less effective,” he explained.

He also warns that people can potentially fall into a pattern of taking more when a product no longer seems to work as well.

Does taking a sleeping pill change the quality of your sleep?

It’s not simply about how many hours you spend asleep.

Sleep scientist Hannah Shore, of Mattress Online, explains that sleep is made up of different stages, each contributing to different aspects of recovery.

“REM and lighter sleep help your brain recover, sorting and storing memories, helping with learning and emotional processing,” she explained.

“Deeper sleep helps the body recover physically.”

Some sedative medications can alter the structure and stages of sleep, potentially changing the balance of REM, lighter and deeper sleep. This may contribute to some people feeling confused, groggy or irritable the following day.

Why women’s sleep needs more attention

Shore also points out that sleep research has historically focused heavily on male participants, with findings often applied more broadly.

“Hormonal changes, menstrual cycles, pregnancy, and menopause can all influence sleep, meaning women can experience sleep differently from men so of course their needs differ,” she explained.

Sleep apnoea, for example, can present differently in women than in men, meaning some women may not be identified using traditional screening approaches.

“When standard screening techniques don’t identify the underlying issue, doctors can be left with a one-size-fits-all approach of prescribing sleeping tablets,” Shore said.

“This often doesn’t solve the underlying issue; instead, it can provide a mask, leaving the cause of the sleeping problem unaddressed.”

Are sleeping pills ever worth taking?

The experts aren’t suggesting that sleeping tablets should never be used.

For some people experiencing severe, short-term insomnia, medication can provide valuable relief and help break a period of sleep deprivation.

But prescription sleeping tablets such as zopiclone also carry a risk of dependence and are generally intended for short-term use.

Dr Shoka says: “Small courses have a place for genuine short-term insomnia. But they’re not a tool for nightly use.”

Shore agrees that sleeping medication can have a role when appropriately prescribed, but says the underlying reason for someone’s sleep problems should also be investigated.

“You should be working with medical and sleep professionals to ensure you get to the root cause of your sleep issue, rather than masking it with supplements and medication, which may cause more issues further down the line.”