Scientists have found a switch in the brain that appears to control anxiety and wakefulness.
Drugs could target the switch
In tests on rodents, the University of California team found a protein called NPS was active in areas of the brain governing arousal and anxiety.
This switch could be a target for drugs to treat sleep and anxiety disorders and attention deficit hyperactivity disorder, they hope.
The findings appear in the journal Neuron.
Scientists had recently discovered the brain protein neuropeptide S (NPS), but had not fully explored its actions.
Dr Rainer Reinscheid and colleagues looked at the activity of NPS in the brains of rodents and found it was produced in a few discrete brain regions.
One of these was a region of the brain stem which is known to be important in regulating sleep and anxiety.
Neurons in this area fire signals to promote arousal and are inactive during periods of sleep.
When the scientists injected mice with NPS they became more active and showed fewer anxiety responses to stressful situations.
When rats were injected with NPS they became more alert, sleeping less.
By identifying where NPS is active and how it affects the brain the researchers said it might now be possible to develop drugs to target the same pathways.
Dr Reinscheid said: "We've found NPS to be so active with sleep and anxiety behaviour that it can be a very attractive drug target, both to enhance and to suppress its function."
It might lead to treatments for a condition called narcolepsy that causes excessive daytime sleepiness attacks, or anxiety disorders, he said.
"It's an important step to describe such a fundamental process because we spend a third of our time sleeping," he said.
But he added: "This is at a very early stage. Treatments would be five to 10 years down the road."
He said their next step was to investigate what would happen if someone was lacking this switch.
They could do this by looking at animal models, he said.
Alison Cobb, spokewoman for Mind, said: " Any advance in understanding brain chemistry and function is welcome, but as this research is still based on mice it is at a much earlier stage than drug development.
"If treatments are developed which improve on current sleeping pills, it is important that they are still used with caution as it takes time for a full profile of side effects to emerge.
"Sleep problems are very common, and although they can be severe and intractable, talking up the potential of new drug therapies risks medicalising a problem that can be tackled in other ways."