Sleeping Too Little Puts Us at Risk of Alzheimer’s Disease?!!

We are often told we need 8 hours of sleep every day. Do you wonder where the number comes from? Well, it seems the number is quite random. There is no definitive length of time for sleep, says an anthropologist.

WORDS PANK JIT SIN

FEATURED EXPERT DR DAVID R SAMSON Director of the Sleep and Human Evolution Lab Department of Anthropology University of Toronto Mississauga

Dr David R Samson said he could not find evidence for the amount of sleep a person needs.

“Most numbers seem to have been given arbitrarily,” he says.

7 HOURS INSTEAD OF 8?

Humans sleep the least amount compared to other members of the primate order.

However, by comparing human biology to those of close primates, he arrived at an estimated figure of about 7 hours per night.

OUR SLEEP PATTERN HAS NOT CAUGHT UP WITH THE MODERN AGE

As humans enter the modern age, we tend to forget that our biology has not caught up with the changes brought about by modernity.

For instance, our primate cousins are used to almost pitch-black nights.

In today’s scenario, however, pitch-black nights are a rarity — at least in urban areas — since we have lights in the street, hall, and room. To compound matters, our computers and mobile devices also emit blue light, which is a component of sunlight.

However, being exposed to blue light tricks our biological clock into thinking it is still daytime and thus not the right time to fall asleep.

The effect of modernization on people can be clearly seen when compared to populations still living in natural surroundings without technology or pollution.

In his studies of the hunter-gatherer Hadza people of Tanzania, Dr Samson discovered they slept about 6.4 hours each night.

While this is not a long period of sleep, what’s important to note is that these people have a very strong circadian rhythm, which means they sleep and wake up at the same time each day.

This rigid circadian rhythm may be the reason behind their relatively long lifespan — averaging about 60 plus years.

Dr Samson said the lifespan of 60 over years may seem rather short to city dwellers but for people with no access to basic healthcare and vaccination, it is a long lifespan.

CIRCADIAN RHYTHM SLEEP DISORDERS

Sleepiness is just one of many circadian rhythm sleep disorders (CRSDs), which also include insomnia or the inability to fall asleep.

The ones we rarely hear about are circadian phase disorder and seasonal affective disorder.

Circadian Rhythm Disorder

• This is the type of disorder usually affecting adolescents and college students, where their night owl tendencies disrupt the internal body clock.
• As a result, the affected individual experiences insomnia at night and excessive sleepiness in the day which lead to disruption to work, school or even social interactions.

Seasonal Affective Disorders

• These are less likely to affect Malaysians living in the tropics as we do not have clear transition of seasons similar to those in temperate countries.

WATCH THE LIGHT

Many individuals go to work or school early and stay indoors until late evening, thus receiving little natural light.

As a result, the body’s circadian rhythm finds it hard to detect the difference between day and night times.

Get Some Sunlight

Light in the blue wavelengths boosts attention, reaction time and mood.

• Thus, Dr Samson suggests that we have at least one meal (breakfast or lunch) outside under the sun.
• He says: “It is easy for Malaysians to eat in the open. In temperate countries like Canada, sometimes we have only 1 or 2 hours of sun a day.”

Shut Off Screen Devices

• When winding down to sleep, it is best to shut down all screen devices, especially mobile phones, which emit blue light.
• This is because constant bombardment of blue light can make it hard to wind down and fall asleep.
• This is due to the blue light’s ability to suppress melatonin secretion.