Shallow sleep can impair a person's glucose metabolism, despite the presence of adequate insulin, researchers report. The finding might explain previous studies that linked poor sleep patterns with type 2, or adult-onset, diabetes, since the disease is closely tied to such insulin resistance.
Researcher Esra Tasali of the University of Chicago monitored nine healthy volunteers during two nights of sleep. She also used blood tests to measure each participant's ability to process intravenous infusions of glucose the next morning. A month later, Tasali repeated the tests over three nights. But this time, researchers set off a noise whenever a participant entered a deep form of sleep thought to be the most restorative. The disruptions pull people back from deep sleep but don't awaken them.
The blood tests showed that eight of the nine volunteers had significantly poorer glucose processing the day after being deprived of deep sleep. In these people, insulin-making cells in t