THE SEVEN AGES OF SLEEP PATTERNS

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.

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.

4ADOLESCENTS (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.

5ADULTHOOD (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.

6HEALTHY

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.

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.