Adding sleep to the weight debate
by Geraldine Hinter
Children
and adolescents are sleeping less than ever before and emerging
evidence shows that sleep deprivation has a profound effect on
weight regulating hormones, adding to weight gain.
Senior lecturer in human movement and health studies at UniSA’s School of Health Sciences, Dr Graham Dodd has led a major review of research related to the impact that sleep duration has on weight gain and its effect on the health and wellbeing of children and adolescents.
"Sleep provides more benefits than previously thought. It is a dynamic activity with many processes vital to health and wellbeing," Dr Dodd said.
"The time spent asleep plays a direct role in how energetic and successful the waking hours are. Getting enough sleep refers directly to the amount of sleep required to not feel tired and be able to perform at an optimum level the next day."
It is an area of special interest to Dr Dodd who, with colleague
Dr Jim Dollman and Paediatric Sleep Research Fellow Dr Sarah Blunden
from the Centre for Sleep Research, is a member of UniSA’s
newly-formed paediatric wellness cluster which focuses on three
interlocking circles of nutrition, activity and sleep as important
ingredients in the health and wellbeing of children.
"During sleep many important hormones are secreted that affect growth, regulate energy and control metabolic and endocrine functions. Of particular interest in the weight debate are the hormones leptin and ghrelin, which influence appetite and hunger."
University of Chicago studies in 2004 showed that when people don’t get enough sleep, they not only produce lower levels of leptin, which causes a craving for carbohydrates regardless of the amount of calories consumed, and increased levels of ghrelin, which stimulates appetite, but also higher levels of body fat.
"The imbalance of these hormones associated with shortened sleep
contributes
to the obesity epidemic,"
Dr Dodd said.
"Getting sufficient sleep gives the body a chance to reach its desirable core temperature (homeostasis), which is essential for the hormones to work effectively, and for a whole range of functions within the body that are crucial to the way we operate.
"It appears boys may be more susceptible than girls and younger children may be more susceptible than older children to this assault on bodily functions caused by sleep deprivation."
Dr Dodd said that increased knowledge about the relationship between sleep deprivation and being overweight or obese is particularly important for health and physical education teachers, whose focus is on the health and wellbeing of their students.
"Where there is a tendency for kids to be overweight, one strategy for health and PE teachers could be to encourage them to get longer sleep in addition to diet and physical activity," Dr Dodd said.
"We’re suggesting that teachers look for signs of sleep deprivation in kids and talk with them individually about their sleep-wake schedules. Information on sleep needs should be included in school programs and students should be encouraged to achieve and maintain age appropriate sleep schedules as outlined in the recommended guidelines from the National Sleep Foundation (2000).
"The recommended hours of sleep for children aged three to five years are 11 to 13 hours, five to 12 years are nine to 11 hours, and adolescents and adults should get between 8.5 to 9.5 hours sleep, which should be maintained for life."
To achieve these sleep schedules, Dr Dodd says parents need to be actively involved in getting their kids to adopt good sleep hygiene. This includes getting good regular bedtime routines, the right bedroom environment – noise, light and temperature, eliminate night-time eating and drinking habits, and reduce activities such as TV and computer usage before bed.
Dr Dodd conducted the study with UniSA researchers Dr Jim Dollman (School of Health Sciences) and Assoc Prof Kurt Lushington (School of Psychology), Assoc Prof Daniel Agley from Towson University Maryland USA, and PhD student Sarah Biggs from Adelaide University.