14 DAY TRIAL // Bad sleep is worse than low cognitive abilities, weight gain, bad sex and car crashes. A team from the University of Warwick, and University College London, has discovered that less sleep doubles your chances of dying from cardiovascular disease. But too much sleep also doubles the risk of death.
The research was made on 10,308 civil servants in the "Whitehall II study" and employed data on the mortality rates and sleep patterns on the same subjects at two moments in their life (1985-8 and those surviving in 1992-3).
The team considered other factors like age, sex, marital status, employment grade, smoking, life style, alcohol consumption, overall health, body mass index, blood pressure, cholesterol. After analyzing those factors, the researchers could see that changes in sleep patterns over 5 years affected mortality rates 11-17 years later.
Those who did not have any change in their sleeping patterns between 1985-8 and 1992-3 were used as baseline (7 hours per night was considered the appropriate sleep time for an adult), and this is how the researchers could assess the way a decrease in sleeping amount over time impacted the mortality rates by 2004.
A sleep cut from 7 to 5 hours or less displayed a 1.7 times higher risk in mortality from various causes and 2 times from a cardiovascular issue.
"Fewer hours sleep and greater levels of sleep disturbance have become widespread in industrialized societies. This change, largely the result of sleep curtailment to create more time for leisure and shift-work, has meant that reports of fatigue, tiredness and excessive daytime sleepiness are more common than a few decades ago. Sleep represents the daily process of physiological restitution and recovery, and lack of sleep has far-reaching effects." said lead researcher Professor Francesco Cappuccio from the University of Warwick's Warwick Medical School.
But too much sleep too had a negative effect: those who had an increase in sleep time to at least 8 hours a night were over 2 times more likely to die, but not from cardiovascular diseases.
"Short sleep has been shown to be a risk factor for weight gain, hypertension and Type 2 diabetes sometimes leading to mortality but in contrast to the short sleep-mortality association it appears that no potential mechanisms by which long sleep could be associated with increased mortality have yet been investigated. Some candidate causes for this include depression, low socioeconomic status and cancer-related fatigue. In terms of prevention, our findings indicate that consistently sleeping around 7 hours per night is optimal for health and a sustained reduction may predispose to ill-health." said Cappuccio.