The study, which included seven young adult subjects, was tightly controlled. All participants were required to stay in bed for the entire three-day study. Their diets met individual daily energy requirements, and the content and timing of each meal was exactly at the same time each day during the lab study. The subjects spent the sleep deprivation night in bed watching movies, reading and talking, said Wright.
The first day of the study consisted of a typical 16 hours of wakefulness followed by eight hours of sleep. Days two and three included 40 hours of total sleep deprivation followed by eight hours of recovery sleep.
As part of the study, the researchers studied the effects of sleep stages ranging from light sleep to rapid-eye movement sleep to deep, "slow wave" sleep and awakenings from sleep on whole body energy expenditure, Wright said. The study indicated the most energy was expended during natural arousals from sleep, which occurred less often during the eight-hour sleep episodes following sleep deprivation.
The amount of energy saved during sleep by the study subjects likely would have been higher if they were allowed to continue sleeping after the eight hours of recovery sleep rather than being awakened, which was the final step in the study, said Wright.
The study may have implications for those with sleep disorders such as insomnia or sleep apnea. Insomnia, marked by difficulty going to and staying asleep, and sleep apnea, marked by frequent arousals from sleep, may mean such people "are burning the furnace at a higher rate at night because their sleep is disturbed," said Wright. He noted that more research is needed to address this issue in patients with sleep disorders.
It's likely that the metabolic costs of sleep deprivation would have been higher if the subjects had not been restr
|Contact: Kenneth Wright|
University of Colorado at Boulder