Too little shut-eye a time bomb for the heart
Deprive yourself of sleep and you may be more likely to eat junk food, have higher anxiety levels and raise your risk for stroke symptoms. So say findings from three separate studies presented over the weekend at the 26th annual meeting of the Associated Professional Sleep Societies in Boston.
In the first study, 25 men and women of normal weight were either restricted to four hours' sleep or allowed to have up to nine hours' sleep for five straight nights. After that, they looked at images of healthy and unhealthy foods while undergoing a brain scan.
The researchers, from St Luke's-Roosevelt Hospital Centre and Columbia University in New York, found that the sight of unhealthy food during a period of sleep restriction activated reward centres in the brain that were less active after adequate sleep.
'Indeed, food intake data from this same study showed that participants ate more overall and consumed more fat after a period of sleep restriction compared to regular sleep,' says Marie-Pierre St-Onge, the study's principal investigator.
Brain scans were also used in the second study by the University of California, Berkeley, to analyse the effect of sleep deprivation on anticipatory activity in deep emotional brain centres.
The scans were done on 18 healthy adults in two separate sessions, one after a normal night's sleep and a second after a night of sleep deprivation. During both sessions, participants were exposed to an emotional task that involved a period of anticipating a potentially negative experience (an unpleasant visual image) or a potentially benign experience (a neutral visual image).
Results showed that sleep loss exaggerated the degree to which participants anticipated impending emotional events, particularly among those who were highly anxious.
In the final study, researchers at the University of Alabama in Birmingham found that habitually sleeping fewer than six hours a night increases the risk of stroke symptoms among middle-aged to older adults, who are of normal weight and at low risk for obstructive sleep apnea.
The study tracked 5,666 people for up to three years. 'We speculate that short sleep duration is a precursor to traditional stroke risk factors, and once these traditional stroke risk factors are present, then perhaps they become stronger risk factors than sleep duration alone,' says lead author Megan Ruiter.