Some scientists believe our sleep duration has decreased by one to two hours per night in only five decades. A survey of American sleeping habits from the 1960s – a time when distractions like late night television and the Internet didn’t exist – revealed that most respondents got an average of eight-and-a-half hours’ sleep. By contrast, most surveys today put the average sleep time of Americans at six or seven hours. It is fair to assume that we in Australia don’t fare any better.
We spend one-third of our lives asleep. To busy, active people this may seem like a waste of time, and sleep is the first thing they sacrifice – often, ironically, to make way for other health-giving pursuits such as an early morning workout at the gym. But sleep is as crucial to good health as what you eat – and a lack of it can make you ill more quickly than a lack of food.
Why do we need it?
Sleep is vital for cell regeneration, metabolism, immune function and memory, to name a few important functions. If we go without sleep, we accumulate a sleep debt – that is, our bodies remember how little sleep we’ve had, and each time we lose sleep, it is added to the ‘score’. The less we have, the more we need in order to recover that debt.
Signs of sleep debt are obvious – fatigue, irritability, the need for coffee and other stimulants to get through the day, a tired appearance. At the more extreme end of the scale, sleep deprivation can cause cognitive impairment, memory lapses, decreased reaction times and, ultimately, an impaired immune system.
There is growing evidence to suggest that a long-term lack of sleep contributes to some of the big illnesses in our society – heart disease, diabetes, depression and even obesity. Studies have shown that people who don’t get enough sleep don’t live as long as people who do.
Lack of sleep can make you fat. Studies have found that a good night’s sleep helps to regulate appetite. Researchers at Bristol University in the UK investigated the role of two key metabolic hormones that regulate appetite – ghrelin and leptin. Ghrelin increases feelings of hunger, while leptin suppresses appetite. The study found that people who habitually slept for five hours had 15 per cent more ghrelin and 15 per cent less leptin than those who slept for eight hours. This meant people felt hungrier if they had had less sleep.
Dr Shahrad Taheri, lead author of the study, says: “These differences are likely to increase appetite and, in societies where food is readily available, this may contribute to obesity. Individuals who spent less than eight hours sleeping were shown to have a greater likelihood of being heavier. Good sleep, in combination with other lifestyle modifications, may be important in fighting obesity.”
Sleep makes you smart
Sleep plays a role in helping us to process and store information. Dr Robert Stickgold at the Division of Sleep Medicine at Harvard Medical School says sleep is important before you try to learn something, but it is also important after. Sleep helps to synthesise information into memories that can be used by our brains.
“If your brain is too tired it can’t take information in as well. After you have learnt something, the brain still has to do a lot of work with that memory to get it into a form where it’s going to be stable and useful to you.”
Eating for sleep
As a rule, a full stomach will make you drowsy. Some sleep counsellors suggest that you stay alert with light meals during the day, and make the evening meal the major meal. Nevertheless, it is wise to schedule it at least four hours before you plan to go to sleep, to ensure your digestive system doesn’t keep you awake.
Warm milk has long been considered a sleep inducer. Milk contains an essential amino acid, tryptophan, which stimulates the brain chemical serotonin, believed to play a key role in inducing sleep. This effect can be enhanced if the milk is consumed with a piece of whole-wheat bread, or another carbohydrate. Other foods to consider are:
- Whole grain carbohydrates such as oats, rice or pasta
- Chlorophyll-rich foods such as leafy green vegetables
- Some teas such as chamomile and lemon, which calm the mind
- Herbs such as basil and dill
Some foods act as stimulants; others may produce hyperactivity or disturb digestion in ways that affect sleep. Consider avoiding the following in the hours before bedtime:
- Coffee, tea and any products containing caffeine – for example, chocolate
- Cured meats
- Foods high in additives and preservatives
- Canned foods, which can be high in toxicity and heavy metals
- Alcohol – particularly red wine and beer
- Sugar and refined carbohydrates. These raise blood-sugar levels and can cause a burst of energy that disturbs sleep.
Strategies for sleep
Ensure your sleeping environment is uncluttered and tranquil, and doesn’t contain anything that might set your mind racing – for example, a laptop containing unfinished work! Televisions are also a no-no in a peaceful sleeping environment. Make sure the temperature of the room is cool, and rug up with extra blankets. Scientists believe you get a better night’s sleep if your environment is not overheated. Also check that you’re not drying out at night – a humidifier can correct this problem, and that noise and light are shut out.
Don’t sleep in to compensate
Don’t sleep in if you’ve had a bad night’s sleep. Your sleeping patterns will only adjust so you’re going to bed later and getting up later. It is crucial to get up and stay up even after you have lost sleep. For similar reasons, avoid taking naps during the day.
Set your body clock
Try to go to bed at about the same time every night. Be regular – most people get hungry around regular mealtimes because they’ve eaten at those times for years. Light helps restart your body clock to its active daytime phase. So when you get up, go outside and get some sunlight. Or if that’s difficult, turn on all the lights in your room. Then walk around for a few minutes. The calves of your legs act as pumps and get blood circulating, carrying more oxygen to your brain to help get you going.
Being inactive is one of the worst things an insomniac can do. It is important to keep physically active during the day, especially the day after a bad night’s sleep. The less you sleep, the more you should be exercising to encourage sleepiness the following night. Strenuous exercise (such as brisk walking, swimming or jogging) in the late afternoon seems to promote more restful sleep. Insomniacs also tend to be inactive a couple of hours before bed, so try some gentle exercise such as stretching or yoga.
Make bedtime sleep time
Go to bed later when you are having trouble sleeping. If you’re only getting five hours of sleep a night during a bad patch, don’t go to bed until just five hours before your wake-up time. For instance, if you’ve been waking up at 7am, don’t go to bed until 2am. Then, as your time in bed becomes good sleep time, move your going-to-bed time back 15 to 30 minutes a night and do that for a week or so. This is the opposite of what most people try to do to relieve insomnia: they go to bed earlier to make up the lost sleep.
Get into a routine
Don’t get into any stimulating discussions or activities a half hour or hour before bed. Do something relaxing: read something ‘light’, do some yoga or relaxation exercises, listen to quiet music, watch a mindless TV show. Have a warm bath, but avoid showers, which can wake you up.
Put it on paper
Keep a pad and pencil handy. If you think of something you want to remember, jot it down. Then let the thought go. There will be no need to lie awake worrying about remembering it.