New York, Aug 16 (IANS): Know why do you feel drowsy after a bad night's sleep? The answer lies in a few nerve cells in you brain that may control the switch between internal thoughts and external distractions.

A critical part of the brain called thalamic reticular nucleus (TRN) that influences consciousness holds the key.

To understand how the brain switchboard works, researchers used lasers to study the firing patterns of TRN cells in mice during sleep and arousal - two states with very different information processing needs.

The results suggest that the TRN has many switchboard operators, each dedicated to controlling specific lines of communication.

Using this information, researchers could alter the attention span of mice.

“Now we may have a handle on how this tiny part of the brain exerts tremendous control over our thoughts and perceptions,” said Michael Halassa, an assistant professor at New York University's Langone Medical Centre.

These results may be a gateway into understanding the circuitry that underlies neuropsychiatric disorders.

The TRN cells are thought to act as switchboard operators that control the flow of information relayed from the thalamus to the cortex.

“The future of brain research is in studying circuits that are critical for brain health and these results may take us a step further,” said James Gnadt, programme director at the US National Institute Neurological Disorders and Stroke (NINDS).

The findings appeared in the journal Cell.