Getting a good nights’ sleep is important for overall health, but a new study has found millions of people could be putting their safety at risk because their prescription sleeping tablets work too well.
A trial of one of the main class of prescription sleeping pills has found that half of participants slept through a fire alarm as loud as someone vacuuming next to their bed. The study, published in the Frontiers in Behavioural Neuroscience Journal, found the most widely prescribed class of sleeping pills known as benzodiazepines make people less likely to wake – even in response to sensory input.
In Australia, commonly prescribed benzodiazepines include nitrazepam, diazepam, oxazepam and alprazolam, while bromazepam, clobazam, clonazepam, flunitrazepam, lorazepam, and triazolam are also popular.
“Benzodiazepines stimulate the widespread brain receptor GABA-A, which makes us sleepy but also suppresses off-target brain areas – including the ‘gatekeeper’ that decides which sensory inputs to process,” senior author of the study Tomoyuki Kuwaki explained.
Because of this, researchers have been developing a new class of hypnotic medications. Known as dual orexin receptor antagonists (DORAs), the drugs differ from benzodiazepines by targeting the brain’s sleep and wake pathways.
By doing this, researchers are also hopeful DORAs may also reduce the drowsy side effects many people using sleeping tablets experience the day after. Other common side effects ofbenzodiazepines include confusion, dizziness, trembling, problems with vision and even depression.
Kuwaki and his research team believe that in addition to reducing these side effects, DORAs could benefit people while they’re asleep by allowing the brain’s sensory gatekeeper to stay vigilant to threats.
To test their theory, researchers used experimental hypnotic drug DORA-22 on mice. One group was given DORA-22, the second used triazolam and the third was given a placebo. Researchers found both DORA-22 and triazolam extended the duration of a deep sleep by up to 40 per cent, compared to the placebo.
Between an hour and four hours after being given their sleeping medication, deep-sleeping mice were presented with a threatening stimulus of either the smell of a fox, a high-pitched noise or the trembling of their cage. The trembling of their cage was to mimic an earthquake, which is a serious threat to humans in parts of the world.
“As expected, arousal in response to these threatening stimuli was delayed significantly in the triazolam treatment, but not in the DORA-22 treatment, compared to a placebo,” Kuwaki said. “Even though the DORA-22-treated mice were quickly woken by a threat, they subsequently fell back asleep as quickly as with triazolam, and significantly faster than with placebo.”
In order to demonstrate that the waking delay in the mice given triazolam was due to inhibition of sensory gating in the brain, a non-sensory stimulus was also used on the mice. Because all three groups woke equally quickly when the oxygen levels in their cage was reduced, researchers believe the delay in mice taking triazolam was not caused by a general inhibition of waking systems in the brain.
The next step for researchers is to test the drug on humans as it is not yet known if DORAs have the same properties in people. While a type of DORA known as surovexant has gained regulatory approval in Australia, the US and Japan, it remains expensive with little clinical testing.
Researchers believe surovexant, like benzodiazepines, can cause drowsiness in people the following day, which is why they’re hopeful new DORAs will work in human trials as an effective way of stopping side effects associated with sleeping pills.
It’s always important to talk to a GP or health professional before taking sleeping medication and to discuss possible side effects with a them before taking medication.
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