How well we sleep — and when — is very much determined by our body clock. And the body clock, as I explained in yesterday’s Mail, is regulated by sunrise and sunset: our exposure to light and darkness ‘tells’ the clock in the brain when it is the best time for sleep and wake.
Problems with sleep, such as insomnia, are often down to problems with the body clock — typically as a result of the wrong light exposure linked to our 24/7 culture where we try to squeeze more into our days and nights.
But the body clock is not the only driver of sleep.
The second key driver is called ‘sleep pressure’. This builds from the moment we wake and rises throughout the day and reaches its highest level in the evening prior to sleep.
Problems with sleep, such as insomnia, are often down to problems with the body clock — typically as a result of the wrong light exposure linked to our 24/7 culture where we try to squeeze more into our days and nights
We fall asleep naturally when the body clock drive for us to be awake drops, and the sleep pressure is high.
Then, as we sleep, sleep pressure declines — and the body clock instructs the brain, and the rest of the body, that it is time to wake up.
THE PERILS OF COFFEE ON THE GO
So what drives sleep pressure? One theory is that it’s down to the build-up of chemicals in the brain. The most likely contender is a molecule called adenosine, which animal studies have shown increases during periods of wakefulness and is then broken down during sleep.
The brain seems to use adenosine levels as a minute-to-minute measure of how long you have been awake. The reason caffeine — in the form of coffee, tea or chocolate — keeps us awake and alert is that it blocks the mechanisms in the brain that detect adenosine.
This means the brain cannot detect how tired it is even when adenosine levels are raised.
But while the short-term use of caffeinated drinks can be useful in keeping us awake during long motorway journeys, for instance, you need to be careful, because as the effects of caffeine wear off we can experience a wave of profound and overwhelming tiredness that can cause us to fall asleep at the wheel.
This is why you need a steady infusion of caffeine if you are on a long trip. Either way the bottom line is, don’t drive if you are tired.
While the short-term use of caffeinated drinks can be useful in keeping us awake during long motorway journeys, for instance, you need to be careful
The body clock and sleep pressure do not act alone — additional factors, including our genes, our emotional state and our age (see panel), combine to deliver the sleep and wake pattern that we get.
And any of these can also alter that pattern, leading to sleep problems.
Today, I look at some of the most common sleep issues, in particular insomnia, and what you can do to tackle them.
YOU MAY NOT HAVE A PROBLEM
One of the main causes of sleep problems is a ‘faulty’ body clock and, typically, insomnia is the result. ‘Insomnia’ is the term we use medically to describe difficulties falling asleep or staying asleep as long as the individual would like.
But what many people might regard as insomnia may, in fact, be a natural way of sleeping.
Some humans and other animals do not sleep in a single consolidated block of sleep — they have two episodes of sleep (known as biphasic sleep) or even multiple episodes (called polyphasic sleep), where the periods of sleep are separated by short periods of being awake.
People who sleep in this pattern are regarded as suffering from ‘insomnia’. Yet it may be that having a single period of sleep without waking (monophasic sleep) is not, in fact, the normal state of human sleep as many assume — it could be as a result of a shortened night and less opportunity to sleep.
Historical records and laboratory studies where individuals have been exposed to 12 hours of light and 12 hours of darkness support the idea that when we have the opportunity to sleep longer, we revert to polyphasic sleep, with several sleep episodes interrupted by short periods of wakefulness.
This raises the important point: if the natural state of human sleep is polyphasic, then we need to re-think our interpretation of disrupted sleep at night.
Reassuringly, new research suggests that if you wake up at night, most people will fall back to sleep within 30 to 40 minutes or so — as long as you don’t get involved in social media or other ‘alerting’ behaviours. The key point is that waking at night need not mean the end of sleep.
If you do happen to stir from your slumbers in the middle of the night, it is important not to feel anxious because this activates stress responses.
Don’t keep checking the clock or remain in bed getting increasingly frustrated by the failure to sleep. Some people find it useful to get up, keep the lights low and engage in a relaxing activity such as reading or listening to music, then returning to the bed when sleepy again.
Others watch TV or listen to the radio — but be careful and ensure it’s nothing too exciting.
I know people who have a favourite and comforting DVD that works for them.
You may want to try a very light snack such as a plain digestive biscuit or small warm drink, such as milk.
But don’t eat or drink too much — remember the digestive system is prepared for sleep.
What you must never do is check your emails or go on social media.
AVOID SLEEPING PILLS LONG-TERM
Prescription sleeping pills can be useful to try to correct a period of poor sleep — taking a low dose (in consultation with your GP) for a few days or weeks does work for some. But medication will often not address the underlying cause of the sleep problem.
And long-term use of such drugs, known as hypnotics, just masks the issue and can cause problems with side-effects.
For example, benzodiazepines (such as diazepam and lorazepam), which are anti-anxiety medications, increase drowsiness, and are potentially addictive and can affect memory and your ability to concentrate the next day.
Meanwhile, the newer so-called Z-drugs (for example, zopiclone, zaleplon and zolpidem) — which are more commonly used — are faster acting and clear from the system more quickly, so reduce daytime sleepiness.
However, while they are less addictive, they can still cause similar side-effects to benzodiazepines in some people.
The bottom line is that all hypnotics should be used short-term or intermittently and use should be reviewed regularly by your GP.
Prescription sleeping pills can be useful to try to correct a period of poor sleep — taking a low dose (in consultation with your GP) for a few days or weeks does work for some. But medication will often not address the underlying cause of the sleep problem
DON’T FALL INTO THE ALCOHOL TRAP
Some people self-medicate with sedatives such as alcohol. But tolerance builds over time so that you need more and more to get the same sedative effect.
This can lead to multiple problems including impaired reaction times and performance the next day.
Long-term sedation with alcohol will damage the brain and nervous system, heart, liver and pancreas.
Some over-the-counter antihistamines (for example, diphenhydramine or doxylamine found in some over-the-counter night remedies) are also used by many as sedatives.
They’re not as bad as chronic alcohol use but side-effects include daytime sleepiness, dry mouth, blurred vision, constipation and altered bladder function.
Meanwhile, herbal ‘remedies’ such lavender or herbal teas are often recommended to promote sleep.
While these are essentially risk-free, there is no real evidence that they actually promote sleep beyond a placebo effect. However, if they work for you, use them.
Our sleep patterns change as we get older — so the baby who never slept can become the teenager you struggle to rouse; the good sleeper can experience insomnia in their later years.
Here are the seven ‘ages’ of sleep, as I call them, each with their own unique sleep behaviour, problems — and remedies.
1. THE BABY IN THE WOMB
We know that the foetus spends much of its time sleeping. At 32 weeks, your baby sleeps 90 to 95 per cent of the day — we assume because its body is developing and growing and sleep is when these kinds of processes occur as adults.
Interestingly, signals from the mother seem to tell the foetus when it is day and night.
The mother’s sleep changes profoundly during pregnancy, and she can experience increasing insomnia as a result of the physical discomfort, combined with hormonal changes, the need to urinate at night as the baby presses on the bladder, leg cramps, acid reflux and kicks from the baby.
What is not clear is whether the mother’s insomnia leads to insomnia in the developing foetus.
2. INFANTS (0 TO ONE YEAR)
Infants do not begin life with a stable 24-hour sleep and wake pattern as their body clocks are not yet fully developed.
As a result, they spend a total of 16 hours or more a day asleep during the first few weeks.
Over the next few months, sleep gradually becomes more regular.
By six to 12 months, the baby finally has a stable sleep and wake pattern, with a longer stretch of up to nine or more hours at night.
Although 24-hour sleep and wake patterns take months to develop, it’s important the right sleep environment is maintained from the start to help synchronise the body clock. The bedroom should be quiet and as dark as possible at night, using blackout curtains.
Infants do not begin life with a stable 24-hour sleep and wake pattern as their body clocks are not yet fully developed
3. CHILDREN (ONE TO TEN YEARS)
The huge anxiety experienced by many parents is how much sleep their children should get: and the answer is ‘as much as they need’.
Sleep should have the highest priority: in children, it’s particularly important for both health and development.
What we don’t know are the consequences of long-term insufficient sleep during childhood, so why take the gamble?
A reliable measure of whether they’re not getting enough is if they are unruly, recalcitrant or capricious.
Other signs include learning and memory difficulties, anxiety, low mood as well as hyperactivity.
Good sleep practices are essential — and the lighting conditions before and during sleep are critically important. Bright light immediately before bedtime will alert the brain, making it more difficult to go to sleep.
The pre-bedtime ritual should occur under dim light and, ideally, all light should be removed during sleep.
If the child experiences anxiety in the dark, the low light from night-lights is probably fine but don’t use them unless you need to, as increased alertness from visual stimulation may delay sleep.
The number of hours they sleep reduces naturally through childhood, from about 16 hours in infants to an average of eight to nine hours into the teenage years.
4. ADOLESCENTS (TEN TO 18 YEARS)
Sleep patterns change dramatically during adolescence, with sleep becoming delayed by about two to three hours so that your teen may not fall asleep until late into the night.
Then, on weekends (when they don’t have to get up for school), they may not wake up until the afternoon.
Such changes can often
generate conflict and accusations of laziness. In fact, the delay in body clocks of adolescents correlates very closely with the hormonal changes that occur during puberty, and it seems likely that the sex hormones — oestrogen, progesterone and testosterone — somehow interact with the clock.
All children, but particularly males, gradually become more ‘evening types’ throughout their teenage years until their early 20s.
After that time, they start to revert to the more standard societal norms.
Females show a similar pattern but the delay stops a bit earlier.
This delay has important consequences.
Adolescents need lots of sleep — on average it is eight to nine hours each night for optimum brain function, but many of them get much less.
Early wake times for school mean that some have under five hours’ sleep a night.
This can lead to long naps after school and later sleep times that night, and sleeping late at the weekend to catch up on sleep.
This insomnia can predispose adolescents to short- and long-term health problems.
There is clearly a biological basis for this delayed sleep in teenagers but it is exacerbated by social media, computer games and TV.
The advice for teenagers is the same as for adults — and includes, crucially, getting enough light at the same time.
You can find my step-by-step prescription in the Mail tomorrow.
5. ADULTHOOD (19 TO 65 YEARS)
These are the years when we are more likely to experience insomnia as we try to balance family life with career aspirations, squeezing out sleep and ignoring our body clocks.
As we get older, we also experience the increased risk of sleep disorders associated with weight gain such as obstructive sleep apnoea, where the muscles of the airway ‘collapse’ periodically throughout the night, preventing breathing.
This is linked to excess fat around the neck and tongue, as well as drinking too much alcohol.
We also naturally become more morning-types and often we sleep less — several hours a night for some people.
Women generally have more complaints about sleep problems than men, despite actually getting more sleep. The menopause can be a difficult time for sleep with night sweats, mood changes and difficulty falling asleep being a real problem for some.
Post-menopausal women report nearly double the rate of insomnia compared with pre-menopausal women. Yet when their sleep is measured, it’s pre-menopausal women who do worse, suggesting that hormonal changes may affect the perception of sleep.
By the time we get to our 60s, we are getting up and going to bed at about the same time we did when we were ten.
This is possibly because of declining levels of sex hormones.
6. HEALTHY OVER-65s (65 TO 100 YEARS)
Many people experience poorer sleep as they get older, but it’s not necessarily an inevitable part of old age.
Freed of the constraints of work and other pressures, older people can relax, stop worrying and enjoy the sleep they get.
I know several people who are in their 80s and have never slept better — in fact, friends and family are told firmly never to call before noon.
There is the assumption that older people need less sleep.
7. THE DEMENTIA SUFFERER (65 TO 100 YEARS)
Around 50 per cent of those aged 85 years or older will be affected by dementia and this can badly affect their sleep.
This is partly as a result of a loss of cells in the body’s ‘master clock’, the supra- chiasmatic nuclei in the brain, which may disrupt and sometimes flip sleep/wake timing patterns, leading to the dementia patient wandering about at night.
Indeed, disrupted sleep is the main reason for institutionalising a dementia patient, due to both the physical risk of this night wandering and chronic sleep disruption for the carer.
In patients with mild dementia, increasing the amount of daytime light they’re exposed to and providing complete darkness at night can help stabilise sleep/wake patterns, increase cognitive function and improve mood.
Such an approach is not the solution but could provide a simple and inexpensive approach to help carers manage the condition at least in the short term.
It’s true that sleep changes — we certainly experience more broken sleep, sleep a bit shorter at night and it may take longer to get to sleep.
All this leads to an increase in the likelihood of daytime naps — but this is not a problem unless it affects your daytime ability to function.
Interestingly, healthy older people appear to be less affected by sleep loss than those who are younger.
There has been a lot of discussion that older people have more sleep problems because they produce less of the hormone melatonin.
However, the evidence is that prescribing them melatonin pills does not improve their sleep, suggesting that low levels of melatonin are not in themselves the cause of sleep problems.
It is clear that older people do need higher levels of light to reset the body clock every day — and are therefore more vulnerable to timing problems when it comes to sleeping and waking.
This may relate to the amount of light reaching the light-sensitive cells in the eye.
Our research in Oxford has shown that after cataract surgery, where the cloudy lens is replaced with an artificial lens that transmits more light, patients’ sleep and wake timings improved.
So it’s particularly important that older people experience bright, natural light in the morning to set their clock — either by going outside or sitting close to a window.
Another potential problem is temperature regulation. We need to experience a slight drop in core body temperature of 1c to 2c to promote sleep.
If you have poor circulation with cold hands and feet, you cannot lose as much heat from the extremities.
Warming the hands and feet, which dilates the blood vessels and increases body heat loss, increases sleepiness and increases the likelihood of falling asleep.
So Grandma was right: bed socks and mittens are a good idea, as they will increase overall heat loss and help you get to sleep — and then take them off just before you fall asleep when they have achieved this.