Sleep deprivation impairs brain function
The forgetfulness brought on by insomnia may be countered with drugs, research published in Nature suggests.
Experiments on mice found sleep deprivation disturbed the molecular pathway in the part of the brain involved in memory and learning.
But the memory of these sleep-deprived mice improved with a drug which inhibits a certain enzyme, the University of Pennsylvania study found.
Several studies have now shown that sleep is essential for memory function.
The latest study has pinpointed an enzyme involved - and put forward a means of counteracting it.
Two groups of mice were either allowed to rest over a five-hour period or were constantly disturbed by handling.
The sleep-deprived group demonstrated particular problems when it came to performing a basic retrieval test, which they had learned before.
Analysis of activity in the hippocampus - the part of the brain used for memory and learning - found these mice had increased levels of the enzyme PDE4, and reduced levels of the molecule cAMP.
The latter is known to be a key player in forming brain connections - or synapses - as learning gets under way.
But by administering the enzyme inhibitor Rolipram, a drug which can be used to treat depression, these connections were improved.
As well as reducing the concentration of the enzyme PDE4, the researchers were able to reverse the decrease in cAMP.
As a result, some - but not all - of the memory problems exhibited by the mice were improved.
"A major challenge in the field of sleep research has been to determine how the sleep disruptions associated with neurological and psychiatric disorders, ageing and everyday living, affect cognitive function," said lead researcher, Ted Abel.
"The findings presented here define a molecular mechanism underlying the effects of sleep deprivation on hippocampal function at the behavioural and synaptic level."
It is hoped this in turn will create a basis for treatment.
Research published last year used functional magnetic resonance imaging to illustrate how sleep strengthened connections between nerve cells in the brain, and improved memory and performance.
"This work may give us a little more insight into what is going on in the brain, but we really need to be thinking about ways to achieve adequate sleep in the first place - not how to deal with the consequences," said sleep specialist Dr Neil Stanley.
"We are always going to need drugs for people with serious disorders, but we don't want to end up medicalising lifestyles.
"We need to go back to basics and think about the way we as a society lead our lives, and the impact this has on our sleep, rather than looking for a cure."