New Scientist 28Mar2020

The back pagesAlmostthe last word

Night watch

The heallHnlcklngwatdl I got

far Christmas claims to lknDw

whenlamawalmorlnllght,REM

ordalp sleep. Howdaes ltdo thB1

JomesOMr

By ema~ noaddn!ss supplied

!have been the proud owner

of a health-tracldngwatch for

juttaver a fortnight, and it has

become clear to me that it isn't

verygoodattnowingwhether

or not I am asleep.

Several times, it has reported

that my night's sleep started

si.gnificmtlyearlierorfinished

significantly later than was the

reality. It appean to inteq>ret

a periodoflow, stable heart

rate. together with little or

no movement. as light sleep,

provided it ii followed or

preceded by actual sleep.

Ithasoverestimatedmyperiod

of sleep bymorethan2hours

onanumberofoccasions. 'lhese

events have happened whenlhave

yet to goto bed, when I am in bed

but have yet tofallasleep, when

Ihavewokenatnightand been

unable to get back to sleep, and

ewn whenlhavegotup but then

sat quietly for sometime.

Amajor:reason for buying the

device was to monitor my sleep

in an effort to improve my very

poor sleep patterns. My initial

impression after two weeks is

that it isn't fit for purpose.

.RolwanHooper
London.UK
Ilookedintotbisforthechapter
onsleepinmybookSUperiluman:
LtfeattheeJdmnes of mental
and physical ability. I spent the
night in a sleep lab wired up to
an electroencephalograph {EEG),
which directly meas~ brain
waves, but I was also wearing a
sleep tracker.
The sleep tracker, like most on
the market, measured heart rate
and movement. The idea is that
became, furexample, theheart
slows as you move into stage 2
(deep sleep) of our four-stage sleep
cycles, and the body is paralysed

This week's new questions

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during RllM sleep, the tracker can

estimate the stage you are in.

TheEEG,howeve:r,m.easmes

brain waves, so it can cat.egorlcally

show the stage of sleep you are

in. Thepicturethesleeptnclcer

provided of my sleep cycle wasn't

the same as theWIJ aa:wate

picture thatcamefmm the EEG.

Inotherwords,sleeptrackers

guesstimate the stage. and might

be less rellable than dJrect

meuurementwlthEEG.Jfthey

can help you improve the quality

of your sleep, great. If they add

to the anxiety over the quality of

sleep you think you are getting,

perhaps not so good.

AllanAngU&

viaTwttter

I have used a sleep tracker for

around five years. subjectively.

my kids stopped needing a ride

to school in the morning.

Seat ofw.lsdom.

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Hazel.Rlmman

London,, UK

We haven't always believed that

wethintwithourheads. The

andentEgyptianshadsucbapoor

opinion ofthe bnUn that, during

thepmcessofmummifu:ation,

they removed it through the

nostrils and threw it away.

Inandent times, Jews

as&Odatedeachmental function

with a different part ofthe body.

Emotion was located in the

How arethese stones

still aligned with the

sun after all this time?

bowels, w1llpowerfn the heart and

intellect apparently in the kidneys.

Thus, inliteJ&l tnnslations of the

Bible,Psalm16, verse7says: '1will

bless thelordwhohasgivenme

counsel My kidneys instruct me

in the night season."

Pm!rl'hben

Kenilworth. Wtuwi~shl~ UK

Sceptics, and those of like kidney,

knowinthell'heartthatmany

mental attitudes and activities

are linguisticaD.y attnDutecl to

organs far from the head. Some

of the examples we cm put a

finger on are purely metaphorical,

but many must reflect an earlier

view of physiology.

Spenmr~

Hastings-on-Hudson,, New Yorlt, US

Braintlauma-umanywarrion

musthavenotWed since ancient

times-can cause cognitive

disorders. In particular, a blow to

the head, far more than anywhere

else, can render us unconscious.

So, natmall.y. the acute obsener

Aristotle, and his academic

followen for some two millennia.

concluded that the brain is an

organ to cool the blood. and the

seat of intelligence is the heart. ..

wait, what?

Jiric:.DGalen

LesEuam-le-Rol,Fmnce

In the Bible, there ia no mention

of the brain. or of thoughts being

in the head. Instead, thoughts

and emotions were considered

to be associated with the heart (for

instance, Deuteronomy, chapter 6,

verse 5), the liwr (Lamentations 2:n

and the original text of Psalm 16:9),

the bowels (Psalm40:8) and

eventhekidneys(Psalm26:2).

Sometnnslatlona don't bear

this out though. I

I would say its Msults correlate

well with my feelings ofbeing

well rested or not. OVerthe yeau,

it has also collected data that

indicate an improvement after

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