11 July 2011
There is still a lot that we don’t know about sleep.
THERE is a rare disease called Fatal Familial Insomnia (FFI). Patients are unable to sleep, and they ultimately die, usually in their 50s.
In FFI, the thalamus gland in our brains, which plays an important part in blocking input from our senses whilst asleep, is damaged by proteins called prions in FFI. We still don’t know why it happens, nor how to treat or stop this rare disease.
Sleep is so important. Experiments depriving rats of sleep for two weeks result in their deaths.
A recent study looking at people who sleep an average of five hours a day versus those who sleep an average of seven hours a day showed a much higher incidence of hypertension, heart disease, depression and even suicides in the group with less sleep.
What a difference two hours makes.
Different parts of our brain play different roles in maintaining sleep. These include:
·Hypothalamus – governs circadian rhythms, which promote sleep and arousal.
·Pineal gland – produces melatonin, sensing darkness, and prepares brain to sleep.
·Hippocampus – involved in dreams.
·Pons – has a part in arousal and activation of dreams in Rapid Eye Movement (REM).
·Retina of the eye – arousal signal to brain, senses light.
We still don’t know why we need to sleep. We do know of the severe consequences if we don’t get enough sleep. Is sleep a period where the brain’s activity goes very quiet, and it gets its “rest”?
The answer is an emphatic no. Sleep is NOT being unconscious. It is a dynamic state with shifting levels of electricity, and ebbing and flowing of chemicals in the brain.
At night, we cycle several times through ever deeper phases of sleep. In stage 1 (light sleep), we drift in and out of wakefulness. Brain waves then slow down in stage 2, and become extremely slow in stage 3. Dreams then occur in the REM, where heart rate and breathing grow more rapid.
The Spanish are famous for their siestas (cat naps). The timing of the traditional siesta corresponds to a natural post-lunch dip in our circadian rhythms, and studies have shown that people who catnap are generally more productive and may even enjoy lower risk of death from heart disease.
Babies sleep between 12 and 18 hours a day. Interestingly, 50% of their sleep time is in REM dream sleep.
Children usually sleep from 8pm to 6am, averaging about 11 to 13 hours. About 25% of their sleep is in REM sleep. Studies have shown that children who sleep less are more prone to gaining weight, and also have poorer school grades and lower IQs.
Adolescents usually sleep from 1am to 10am, and they require about nine hours of sleep. Less sleep has again been implicated in poorer school grades. Also, early school hours often clash with their natural sleeping times.
Adults typically require 6.5 to 7.5 hours of sleep a night, and their sleeping times are usually between 11pm to 6am. Again, both sleeping shorter or longer than these normal seven hours results in higher morbidity, depression, and obesity.
Short, poor sleep are also novel risk factors for obesity and for type 2 diabetes. Studies have shown that sleep restriction damages the body’s ability to regulate eating by lowering levels of leptin, the hormone that tells the body when it has had enough food, resulting in overeating.
Sleep disruption also causes an increase in insulin resistance in humans (thus causing the body to need higher levels of insulin).
There are, to date, 86 known sleep disorders, the most common of which is Obstructive Sleep Apnoea (OSA). Typically, these patients are either overweight or obese, and most are men. They snore loudly during sleep and have episodes of choking, gasping, and breathing stoppages (apnoeas), usually witnessed by their sleeping partners.
During sleep, their airways collapse and they suffer from oxygen deprivation, resulting in hypertension, and heart attacks. They also experience higher incidences of road traffic accidents due to excessive daytime sleepiness. A recent horrific bus accident in Malaysia involved an overweight bus driver who admitted he was sleepy when the accident occurred. We can only wonder whether he suffers from OSA.
In the UK, the Department of Vehicle Licensing (our JPJ) makes it mandatory for all drivers of commercial vehicles with OSA to undergo treatment for their OSA before their licences are renewed annually.
Insomnia is when somebody cannot sleep or has difficulty falling asleep.
Narcolepsy is the entire opposite. Here, patients sleep at the drop of a hat, anytime throughout the day.
Sleepwalking or somnambulism is when a patient engages in activities that are normally associated with wakefulness (such as eating or dressing), which may include walking, without the conscious knowledge of the subject.
We must recognise the fact that sleep is a valuable commodity. Guard it religiously. Sleep at the recommended hours, for the recommended hours. Keep computers/TVs/CD players/radios out of the bedroom – these are potential sleep distracters.
Keep the bedroom comfortable, neat, clean and quiet. Remember to “cool down” to sleep. Relax for half an hour before sleeping by soaking in a warm tub, listening to some slow, easy music.
We cannot just switch off the computer and jump into beds. Our minds would still be a beehive of activity and many would find it hard to sleep.
Do not take substances like teas, coffees, carbonated drinks, chocolates just before sleeping. They are stimulants because they contain caffeine, which prevents us from falling asleep.
Melatonin is a hormone produced by the pineal gland in the brain, and light directly inhibits the release of melatonin. That is why melatonin is sometimes called the “Dracula of hormones” – it only comes out in the dark.
Overall, research indicates improved sleep when melatonin is taken at the appropriate time for jet lag and shift work. However, more research needs to be done to see whether melatonin helps in the treatment of insomnia.
In conclusion, I would say that there is still so much we need to find out about sleep. What we do know is that sleep is very important and I wish you all a good night’s sleep!
This article was published in www.thestar.com.my on 27 March 2011.