A Harvard University study claims too little or too much sleep puts older women at a risk for diabetes.
Older women who get too little or even too much sleep are at greater risk of diabetes, new research suggests. The study suggests that chronic short sleep duration of six hours or less, or increasing average sleeping time by two hours or more over a period of several years, increases the risk of developing type 2 diabetes in middle-aged and older women.
Researchers concluded that increasing sleep duration by two hours or more increased the risk of developing type 2 diabetes by 15 per cent -even factoring in variations in diet, physical activity, snoring, sleep apnoea, depression and bodymass index (BMI).
Previous research has shown that too much or too little sleep increases the risk of diabetes, with the lowest risk shown for those who sleep between seven and eight hours per day.
The new study, published in the journal Diabetologia, involved more that 59,000 women aged 55 to 83 in the Nurses’ Health Study -a long term study of current and former nurses from the US -without diabetes in 2000. Change in sleep duration was recorded as the difference between self-reported 24 hour sleep duration in 1986 and 2000. Diet, physical activity and other factors were updated every two to four years. Self-reported diabetes was confirmed and then computer modelling used to evaluate the changes in relative risk of diabetes related to the amount of sleep. Those sleeping six hours or less, as also those who experienced an increase in sleep duration of more than two hours per day, were associated with modest increased risk of developing type 2 diabetes. However, after adjustment for BMI, associations of chronic short sleep duration with diabetes became “non-significant” while associations of increases in sleep duration with diabetes persisted.
The research showed women who increased their sleep duration were more likely to have been short sleepers to begin with, suggesting that the adverse influence of short sleep duration in mid-life may not be compensated for by later increases in sleep duration.
Study leader Doctor Elizabeth Cespedes, of Harvard T H Chan School of Public Health said: “Chronic short sleep duration and increases in sleep duration are associ ated with increased risk of diabetes. Decreases in sleep duration have modest, adverse associations with diet quality and physical activity, while increases in sleep duration have modest, adverse associations with weight gain.
Ongoing trials will provide further insight as to whether changes in sleep duration influence energy balance.”