Recent studies show that the less you sleep, the more likely you are to be overweight. This link is seen in even young children. Staying up to the wee hours might result in more calories before bedtime, but that’s not your only problem.
Sleep deprivation can mess up the body’s metabolic rate and cause an imbalance of two important hormones, ghrelin and leptin. So not only will you feel hungrier the following day, your ability to burn calories slows down too. The resulting tiredness makes you more likely to slink onto the couch and avoid exercise too.
Sleep deprivation leads to more ghrelin (hunger) and less leptin (satiety). Skipping breakfast, when you eventually get up out of bed, can in turn increase the hunger hormone ghrelin, which encourages snacking, often on high-calorie snack foods later on.
Protective genes
Genes that protected us from famines for millions of years control a small area in the middle of the brain called the hypothalamus. This part of the brain helps control our metabolic rate, hunger and satiety.
There are two significant cell types in the hypothalamus. The first is called NPY/AGRP, otherwise known as the hunger cell. When it is stimulated you feel hungry and your metabolic rate drops.
The second cell type is POMC or satiety cell. When it is stimulated you feel full and your metabolic rate increases.
The two key hormones that control the hunger and satiety cells are ghrelin and leptin. Ghrelin is produced by the stomach (think of your tummy growling) and travels to the brain where it turns on the hunger cell and turns off the satiety cell.
Leptin is produced by the fat cells of the body and travels to the brain where it turns on the satiety cell (when you’ve had enough) and turns off the hunger cell.
When you are very overweight you have lots of fat cells and your leptin levels are high. Your brain should register that you have ample body fat stores and switch off the hunger cells.
However, high leptin levels over time make the satiety cell insensitive to leptin and, unfortunately, the opposite effect occurs. Despite the fact that leptin levels are high and the ghrelin levels are low, the hunger cells (eat more) are turned on and the satiety cells are turned off.
Despite having copious amounts of fat cells and stores, the brain in the very overweight, behaves like it is starving.
Ghrelin is also critical for good sleep. If you don’t have adequate ghrelin, you won’t sleep well.
You dream less and as dreaming promotes leptin production, you will be hungrier and have a lower metabolic rate.
One study reported that subjects who slept for four hours instead of eight had a 40 per cent drop in their leptin levels.
A calorie is a calorie no matter what time of the day or night you eat it. But Todd Burstain, clinical assistant professor of medicine in the University of Iowa, explains that eating late at night decreases your ghrelin levels and it may take several hours before the level is sufficiently high enough to allow you to sleep well.
A recent study in Pediatrics on "Changes in Children's Sleep Duration on Food Intake, Weight, and Leptin" found that during the week when children increased their sleep, they ate fewer calories, weighed less, and had lower fasting levels of the satiety hormone leptin, when compared with the week of decreased sleep.
The lead researcher, Chantelle Hart, suggested that increasing children’s sleep at night could have important implications for prevention and treatment of obesity.
Eat, sleep, move
Avoid very big or rich meals late at night. Try to have dinner two to three
hours before bed. Fatty foods put undue work on the digestive tract and may keep you up. Avoid highly spiced foods. These can make you uncomfortable or cause heartburn.
Eat wholegrain, not refined carbohydrates. These provide essential B vitamins for the production of the neurotransmitter serotonin. Low serotonin levels are linked to poor mood and sleep patterns.
Eat lean, not processed proteins. Lean proteins such as turkey, chicken, beans and seafood contain the amino acid tryptophan, important for the production of serotonin.
Eat healthy omega 3 fats and enough micronutrients. For example, magnesium and iron deficiencies may cause restless leg syndrome which can disrupt sleep.
Cut down on caffeine. It can take up to eight hours for the stimulating effects of caffeine to wear off so try a herbal tea such as camomile or valerian instead to relax.
Cut down on fluid. Drinking too much of any thing will disrupt your sleep if you have to get up several times to go to the bathroom.
Skip the nightcap. Alcohol may help you fall asleep faster, but you may waken up more often and experience less restful sleep.
If you’re hungry before bed, try a light snack before bed which can help promote sleep such as cereal with hot milk, a banana or yoghurt. Milk contains tryptophan, the raw material the brain uses to build both serotonin and melatonin. These are compounds that help us relax and prepare for sleep.
While the amount of tryptophan in a glass of milk may not be enough to cause any real drowsiness, a glass of warm milk warms the body and has comforting connotations with childhood. People sleep better when they are warm because the muscles relax more, so it’s not a bad option to go for before bed.
Don’t be fooled by a relaxing smoke. Nicotine is a stimulant, with effects similar to caffeine.
Have a regular bedtime. Choosing a time when you normally feel tired, so that you don’t toss and turn, can be very difficult for shift workers. If you have to change bedtime, help your body adjust by making the change in small increments.
Aim to get six to seven hours’ sleep each night.
Wake up at the same time daily.
Create a quiet, warm and dark sleep environment.
Turn off the TV, Ipad, smartphone. Try listening to music or a guided meditation instead.
People who sleep less than six hours per night tend to have higher blood pressure, higher blood sugar, greater inflammation, and more obesity than those who sleep longer. Research from the National Sleep Foundation shows that Americans have reduced their hours of sleep from eight in 1960 to just five or six today.
The average calorie consumption has increased in the US over the past 40 years. The rate of stress-related complaints is rising. Exercise rates have fallen.
There are no quick-fixes but it’s fascinating that sleep and the disruption of hormones are pivotal in these co-dependent lifestyle factors.
Paula Mee is lead dietitian at Medfit Proactive Healthcare and a member of the Irish Nutrition and Dietetic Institute.
pmee@medfit.ie; Twitter @paula_mee
