Stress, computers, TV, long work hours and burning the candle at both ends are just some of the things that are stealing our sleep — and it’s making us fat. Nutritionist Cindy Williams investigates an essential element of the weight-loss puzzle.
Sleep is not just a way to fill the night before the next day. Sleep is essential to good health. While we sleep our body releases substances that fight infection, build and repair muscle, control appetite, promote maturation in teenagers and consolidate memory which is important for anyone who is studying. Sleep is not optional, it’s essential.
How much sleep do we need?
Infants need 14-18 hours of sleep and toddlers need 12-14 hours of sleep every 24 hours. Primary school children need 10-12 hours, high school children need nine to 11 hours and adults need seven to nine hours of sleep each night. Older people don’t need any extra sleep but because they tend to sleep lightly and awaken more often during the night, they may need a daytime nap. During times of rapid growth and development such as infancy, childhood, teenage growth spurts and pregnancy our bodies also needs more sleep.
Too little sleep is bad for us
Look at any parent with a new baby and you will see, or be told about, the effects of not enough sleep. It affects our emotions making us moody, anxious, depressed, withdrawn, irritable, aggressive or hyperactive. It can affect our concentration. We forget things, and can find it hard to get organised or sort out difficult problems. Lack of sleep reduces our ability to learn and retain what we have learnt. It reduces our motor co-ordination and weakens our immune systems, making us more likely to get sick.
Just as we have financial debt, we also have sleep debt. Even one hour less sleep a night adds up over the weeks to a sleep debt that we must repay if we want to keep healthy and effective.
The sleep weight-loss connection
Do your children go to bed later than you did as a child? If so, you are not alone. More and more of our children are not getting enough sleep and researchers have linked these shortened sleeping hours with the soaring rates of childhood obesity. One study found that infants who slept less than twelve hours a day were more likely to be overweight as toddlers. The same effect also appears to happen to older children. A study of almost 800 children found that not only were the children in year six who slept shorter hours more likely to be overweight, but those who slept shorter hours in year three were also more likely to be overweight when they reached year six. A recently published New Zealand study of three to seven-year-olds concluded that young children who don’t get enough sleep are at greater risk of becoming overweight and the extra weight is not muscle but fat.
Lack of sleep causes weight gain
Is it that being awake longer means we have more time to eat? Is it that we are so tired we don’t care about healthy choices and just grab a quick fix, high kilojoule ‘energy’ drink or bar in the hope it will wake us up?
Many people notice they eat more when they are sleep deprived, but is this just a psychological way to keep awake? The research says no: less sleep makes the body work differently. In fact, being sleep deprived has a similar effect on the body as being overweight. Both decrease glucose tolerance and insulin sensitivity, and can put you on the downward spiral towards diabetes.
Insomnia is defined as being when you can’t fall asleep or go back to sleep within about thirty minutes, or you wake too early and feel you haven’t had enough sleep. It’s more common in women, and with increasing age. It’s common in shift workers and international travellers whose body clock is disrupted. It can be caused by physical problems such as pain, breathing difficulty, hot flushes in women or illness. Some medications such as those for asthma or high blood pressure may also cause insomnia. Depression, a stressful event or anxiety about relationships, work or finances can cause insomnia. Worrying about not sleeping can make it even worse. As the famous author Charlotte Bronte wrote: A ruffled mind makes a restless pillow.
Sleep and hormones
Did you know?
- One in five of us take 10 minutes or less to fall asleep while one-third of us takes more than half an hour.
- About nine per cent of us manage to wake ourselves up with our own snoring.
- Single people take longer to get to sleep (18 per cent take an hour or more) compared to those with partners (12 per cent).
- One-third of South Islanders are woken by their partner snoring, compared to 26 per cent of New Zealanders overall.
- More people in the North Island (55 per cent) have TVs in their bedrooms compared to 44 per cent in the South Island.
- One per cent of us have a fridge in the bedroom.
Less sleep also alters two key hormones: leptin and ghrelin. Leptin reduces hunger. (This appetite suppressing effect sometimes gets confused in overweight people.) Lack of sleep, especially when associated with stress, reduces leptin levels. Take away the stress and your leptin levels may not alter too much. But the hormone ghrelin is different.
Ghrelin — think gremlin — is the hunger hormone. It tells us that we are hungry and we need to eat more. When we don’t get enough sleep, our body makes more of this weight sabotaging hormone. Even one night of sleep deprivation can be enough to increase ghrelin levels. Ghrelin not only increases hunger, it also reduces energy expenditure and promotes fat retention. In a recent study ten overweight people followed a weight-loss diet and compared the amount of weight they lost during a week of normal sleep and a week of only five-and-a-half hours of sleep. They lost the same amount of weight in each phase — probably because they were in a controlled environment. But on the sleep deprived phase they lost 55 per cent less fat. So lack of sleep could sabotage even your most self-controlled efforts to lose those flabby bits and actually leave you with proportionally more fat and less muscle. As the director of this study put it: “If your goal is to lose fat, skipping sleep is like poking sticks in your bicycle wheels.”
The good news is that we can reverse the effects. A recently published study followed a group of people for six years and found that those who changed from sleeping six or less hours a night to a healthier seven or eight hours slowed down their rate of fat gain.
Are there foods to help you sleep?
Sleep experts suggest the best before-bed snack is a carbohydrate-rich food with a bit of protein. Cereal with reduced-fat milk, some low-fat yoghurt or the traditional cup of warm trim milk are good examples. The effect, however, is probably more to do with being a comfort food than any dramatic physiological effect.
There are some popular remedies people have been trying for generations. But do they actually work?
The theory behind this is that milk contains the amino acid (protein) tryptophan and carbohydrate — both encourage the brain to make the hormone serotonin. Serotonin, often called the calming hormone, is involved in sleep onset, pain sensitivity and mood control. However the amount of tryptophan in milk is small and the way it works in the body is complex. It is more likely that any perceived sleep inducing effects of warm milk are psychological.
Chamomile tea is caffeine-free and is often promoted for its relaxing properties. It’s a good alternative to coffee and black or green tea which all contain caffeine. The body can take up to eight hours to eliminate the stimulating effect of caffeine so keep it as a morning-only drink if you have trouble sleeping.
Some herbal supplements such as valerian are promoted as sleep enhancing. They may help you sleep, but it is best to be cautious as the doses vary and in large doses these can cause side effects just like any other drug.
Tips for a good sleep
- Maintain a routine. Children especially thrive with routine. It could be something like: have a bath or shower, brush teeth, jump into bed, read a story, say prayers, lights out.
- Eat lightly at night. Eat your evening meal at least two hours before bedtime. Keep it light and low in fat and spices. And stay away from alcohol and cigarettes — they both disrupt sleep.
- Go to bed at the same time each night.
- Get up at the same time each morning. If you want a weekend sleep-in, keep it short. This is especially important for teens who can disrupt their body clock by going to bed later and later, and sleeping in longer and longer.
- Sleep at night. If you have to nap during the day keep it to less than one hour.
- Have a warm bath, perhaps with lavender oil.
- Keep the bedroom for sleep and sex. Avoid TV, iPads or any other stimulating screen activities. Don’t write, talk on the phone or eat in bed. Some people find reading a book helps them go to sleep but for others reading may be too stimulating.
- Keep the bedroom cool, dark and quiet. Check your mattress and pillow for comfort.
- If you can’t fall asleep after 20 minutes or so, get up. Go back to bed once you feel tired.
- Develop some strategies to help you deal with worry and use them before you get to the bedroom.
- Do aerobic exercise each day but no closer than an hour before bedtime. A physically tired body sleeps well.