Seven things to know about sleep as the clocks go back

Iran Daily - - Health -

whole range of dis­or­ders.

A re­view of 153 stud­ies with a to­tal of more than five mil­lion par­tic­i­pants found short sleep was sig­nif­i­cantly as­so­ci­ated with di­a­betes, high blood pres­sure, car­dio­vas­cu­lar dis­ease, coro­nary heart dis­ease and obe­sity.

Stud­ies have shown that de­priv­ing peo­ple of enough sleep for only a few nights in a row can be enough to put healthy adults into a pre-di­a­betic state.

Th­ese mod­er­ate lev­els of sleep de­pri­va­tion dam­aged their bod­ies’ abil­ity to con­trol blood glu­cose lev­els.

Vac­cines are less ef­fec­tive when we are sleep de­prived, and sleep de­pri­va­tion sup­presses our im­mune sys­tem mak­ing us more prone to in­fec­tion.

One study found par­tic­i­pants who had fewer than seven hours of sleep were al­most three times more likely to de­velop a cold than those who slept for seven hours or more.

Peo­ple who don’t sleep enough also ap­pear to pro­duce too much of the hor­mone ghre­lin, as­so­ci­ated with feel­ing hun­gry, and not enough of the hor­mone lep­tin, as­so­ci­ated with feel­ing full, which may con­trib­ute to their risk of obe­sity.

There are also links to brain func­tion and even in the long term to de­men­tia.

Pro­fes­sor Shane O’mara ex­plained that toxic de­bris builds up in your brain dur­ing the course of the day and waste is drained from the body dur­ing sleep.

“If you don’t sleep enough, you end up in a mildly con­cussed state.”

The im­pact of sleep­ing too much is less un­der­stood, but we do know it is linked to poorer health in­clud­ing a higher risk of cog­ni­tive de­cline in older adults.

We need dif­fer­ent types of sleep to re­pair our­selves

Af­ter we fall asleep we go through cy­cles of ‘sleep stages’, each cy­cle last­ing be­tween 60 and 100 min­utes.

Each stage plays a dif­fer­ent role in the many pro­cesses that hap­pen in our body dur­ing sleep.

The first stage in each cy­cle is a drowsy, re­laxed state be­tween be­ing awake and sleep­ing — breath­ing slows, mus­cles re­lax, the heart rate drops.

The sec­ond stage is a slightly deeper sleep — you may feel awake and this means that, on many nights, you may be asleep and not know it.

Stage three is deep sleep. It is very hard to wake up dur­ing this pe­riod be­cause it is when there is the low­est amount of ac­tiv­ity in your body.

Stages two and three to­gether are known as slow wave sleep which is usu­ally dream­less.

Af­ter deep sleep we go back to stage two for a few min­utes, and then en­ter dream sleep, also called REM (rapid eye move­ment). As the name sug­gested, this is when dream­ing hap­pens.

In a full sleep cy­cle a per­son goes through all the stages of sleep from one to three, then back down to two briefly, be­fore en­ter­ing REM sleep.

Shift work­ers get sick more of­ten

Shift work has been as­so­ci­ated with a host of health prob­lems. Re­searchers have found shift work­ers who get too lit­tle sleep at the wrong time of day may be in­creas­ing their risk of di­a­betes and obe­sity.

Shift work­ers are sig­nif­i­cantly more likely to re­port ‘fair or bad’ gen­eral health ac­cord­ing to a 2013 NHS study, which also found peo­ple in this group were a lot more likely to have a ‘lim­it­ing long­stand­ing ill­ness’ than those who don’t work shifts.

Peo­ple who work shifts are sig­nif­i­cantly more likely to take time off sick, ac­cord­ing to fig­ures from the Of­fice for Na­tional Statis­tics.

There is a far big­ger gap for non­man­ual work­ers than man­ual work­ers — lack of sleep seems to have a big­ger im­pact on those do­ing more seden­tary jobs.

Many of us are feel­ing more sleep de­prived than ever

To judge from me­dia re­ports, you’d think we were in the grip of a sleep­less­ness epi­demic. But are we re­ally all more sleep de­prived than be­fore?

A big piece of re­search look­ing at data from 15 coun­tries found a very mixed pic­ture. Six showed de­creased sleep du­ra­tion, seven in­creased sleep du­ra­tion and two coun­tries had mixed re­sults.

Lots of an ev­i­dence sug­gested the amount we sleep hasn’t changed that much in re­cent gen­er­a­tions.

But if you ask peo­ple how sleep de­prived they think they are, a dif­fer­ent pic­ture emerges.

So why do so many peo­ple re­port feel­ing tired?

It may be that this prob­lem is con­cen­trated in cer­tain groups, mak­ing the trend harder to pick up on a pop­u­la­tion-wide level.

Sleep prob­lems vary con­sid­er­ably by age and gen­der, ac­cord­ing to one study of 2,000 Bri­tish adults. It found women at al­most every age have more dif­fi­culty get­ting enough sleep than men.

The sexes are more or less level at ado­les­cence but women be­gin to feel sig­nif­i­cantly more sleep de­prived than men dur­ing the years where they may have young chil­dren, while work may be­come more de­mand­ing. The gap then shrinks again later in life.

Caf­feine af­fect sleep du­ra­tion and qual­ity.

Phones are keep­ing teenagers awake

Sleep ex­perts said teenagers need up to 10 hours sleep a night, but al­most half don’t get this much ac­cord­ing to the NHS.

Be­d­rooms are sup­posed to be a place of rest but are in­creas­ingly filled with dis­trac­tions like lap­tops and mo­bile phones, mak­ing it harder for young peo­ple to nod off.

We have more dif­fer­ent types of en­ter­tain­ment on of­fer than ever, mak­ing the temp­ta­tion to stay awake greater.

The blue light emit­ted by elec­tronic de­vices makes us feel less sleepy. And the ac­tiv­ity it­self — be it talk­ing to friends or watch­ing TV —stim­u­lates our brain when it should be wind­ing down.

Morn­ing larks, night owls?

There have al­ways been morn­ing peo­ple and evening peo­ple. We even have ge­netic ev­i­dence that backs this up.

But the in­tro­duc­tion of ar­ti­fi­cial light ap­pears to have ex­ac­er­bated this ef­fect, par­tic­u­larly for peo­ple who pre­fer to stay up late.

If you are al­ready in­clined to­wards be­ing a night owl, ar­ti­fi­cial light will make you stay up even later.

About 30 per­cent of us tend to­wards be­ing morn­ing peo­ple and 30 per­cent to­wards be­ing evening peo­ple, with the other 40 per­cent of us some­where in the mid­dle — although marginally more peo­ple pre­fer early ris­ing to late nights.

We do have some con­trol over our body clocks, how­ever. Those who are nat­u­rally late to bed and late to rise can try re­duc­ing their ex­po­sure to light in the evenings and mak­ing sure they get more light ex­po­sure in the day­time.

*Rachel Schraer and Joey D’urso are BBC jour­nal­ists.


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