WESTCHESTER, Ill. -- Microarray studies have identified numerous genes that change in response to prolonged wakefulness. Determining which transcriptional changes translate into protein changes that are critical for recovery during sleep loss, however, can be challenging. Immunoglobulin binding protein (BiP), a key indicator of endoplasmic reticulum (ER) stress, is instrumental in determining the amount of recovery sleep following enforced wakefulness, according to a study published in the May 1st issue of the journal SLEEP.

The study, conducted by Nirinjini Naidoo, PhD, and colleagues at the University of Pennsylvania, focused on a Drosophila head and brain. The authors discovered that there are substantial increases in the molecular chaperone BiP in Drosophila head and brain after modest periods of sleep deprivation. These increases decline progressively during recovery sleep. However, even after 24 hours following sleep deprivation, there is still a small but significant increase in BiP.

According to Naidoo, changes in BiP levels also affect the amount of recovery sleep following sleep deprivation, although the precise mechanism by which this occurs remain to be elucidated.

"Acute sleep deprivation leads to cellular stress and possibly to low level brain injury, said Naidoo. Activation of the unfolded protein response is one protective mechanism against such injury. If protective mechanisms, such as the unfolded protein response, are attenuated, then following sleep deprivation, animals need to sleep more to recover."