‘Sleep is like a cat – it comes only when you ig­nore it’

Sleep is not just about feel­ing rested. It is vi­tal for our im­mune sys­tems, mem­ory, men­tal health, weight and even our ap­petite

The Irish Times - Tuesday - Health - - Health Sleep - Ge­orge Win­ter

‘Sleep is ar­guably the sin­gle most im­por­tant thing we do every day for nor­mal phys­i­cal and men­tal health, and we’re all sleep­ing about one hour less than our coun­ter­parts did in the 1950s.” That’s the view of con­sul­tant neu­rol­o­gist Dr Kirstie An­der­son, of the New­cas­tle Re­gional Sleep Ser­vice, and one of the UK’s top sleep ex­perts.

An­der­son told The Ir­ish Times that sleep is vi­tal for main­tain­ing nor­mal im­mune func­tion; re­cov­er­ing from mus­cle dam­age, for ex­am­ple, af­ter ex­er­cise; en­sur­ing your cells di­vide nor­mally; con­sol­i­dat­ing mem­ory; en­hanc­ing men­tal health; and help­ing to reg­u­late tem­per­a­ture, weight and ap­petite. “And it’s worth re­mem­ber­ing,” she adds, “that the to­tal amount of sleep we re­quire changes as we age, with the av­er­age adult over 45 years need­ing about seven rather than eight hours of sleep.”

Sleep is not a state of un­con­scious­ness. “Dur­ing the night, you go through non-dream and dream sleep in 90-minute to two-hour cy­cles, with light, non-dream sleep in the first 30-40 min­utes and then deeper so-called ‘slow-wave’ sleep,” An­der­son says.

“Adults spend about 20-25 per cent of the night in this deep slow-wave sleep, where your body is prop­erly relaxed and from which it’s un­pleas­ant to be wo­ken.”

Sleep stud­ies

In the first study of its kind to in­ves­ti­gate sleep-wake cy­cling (SWC) in new­borns, re­searchers from Univer­sity Col­lege Cork and Cork Univer­sity Ma­ter­nity Hos­pi­tal re­cently re­ported in the jour­nal Clin­i­cal Neu­ro­phys­i­ol­ogy that EEG read­ings of healthy in­fants taken within 36 hours of birth demon­strate well-de­vel­oped SWC, dom­i­nated by ac­tive sleep. They state that “in com­par­i­son with in­fants born by vagi­nal de­liv­ery or emer­gency Cae­sarean sec­tion (CS), in­fants de­liv­ered by elec­tive CS be­fore labour demon­strate SWC char­ac­ter­is­tics, which may be re­flec­tive of a lower stress level dur­ing the birth process”.

An­der­son em­pha­sises that sleep is an au­to­matic ac­tion, like breath­ing, and in­som­nia comes from pay­ing too much at­ten­tion to some­thing we shouldn’t have to think about: “To quote from Gil­lian Flynn’s novel Gone Girl, ‘sleep is like a cat – it only comes when you ig­nore it!’”

Ir­ish re­searchers are ad­dress­ing other as­pects of dis­or­dered sleep. Di­eti­tian Dr Conor Ker­ley com­pleted his PhD in the sleep and res­pi­ra­tory de­part­ment at Con­nolly Hos­pi­tal, Blan­chard­stown and is lead au­thor of a re­cent study in the pres­ti­gious med­i­cal jour­nal Sleep on the role of vi­ta­min D in adults with the ob­struc­tive sleep ap­nea syn­drome (OSAS).

OSAS, ac­cord­ing to Ker­ley, is a com­mon yet un­der-recog­nised prob­lem in Ire­land and most of the world: “In OSAS the air­ways close or nar­row re­peat­edly dur­ing sleep, de­creas­ing oxy­gen levels in the blood and caus­ing fre­quent wak­en­ing. If un­treated, OSAS can have se­ri­ous con­se­quences, lead­ing to in­creased inflammation and an in­creased risk of heart dis­ease and di­a­betes.”

Up to 70 per cent of OSAS cases, says Ker­ley, are as­so­ci­ated with be­ing over­weight. “How­ever,” he adds, “OSAS can oc­cur in those with a healthy weight too.”

But why study vi­ta­min D in OSAS? “Be­cause vi­ta­min D has been as­so­ci­ated with many OSAS symp­toms, my re­search group con­ducted a de­tailed study of vi­ta­min D sta­tus in OSAS, find­ing that of 106 adults liv­ing in Dublin with OSAS, all but one per­son had low vi­ta­min D levels. We also found that those with the low­est vi­ta­min D had the most se­vere OSAS and the worst heart func­tion.”

Would a vi­ta­min D sup­ple­ment solve the prob­lem? Ac­cord­ing to Ker­ley, “Our re­search group con­ducted the first ever study of vi­ta­min D sup­ple­men­ta­tion in OSAS. Al­though our study was small, we no­ticed vi­ta­min D sup­ple­ments re­sulted in de­creased choles­terol and inflammation with po­ten­tial ben­e­fits in the long term.

“This re­search was pub­lished in the Jour­nal of Clin­i­cal Sleep Medicine. It’s too early to rec­om­mend sup­ple­ments for ev­ery­body but the idea is promis­ing.

“I ad­vise any­body who’s con­cerned about OSAS to be as­sessed by a sleep physi­cian and to get an overnight sleep study. Any­body with OSAS should main­tain a healthy weight, un­der­take reg­u­lar ex­er­cise and con­sider get­ting a vi­ta­min D blood test.”

Obe­sity link

Dr Liam Do­herty, con­sul­tant physi­cian in res­pi­ra­tory and gen­eral in­ter­nal medicine at Bon Se­cours Hos­pi­tal, Cork, has a specialist in­ter­est in sleep medicine. He told The Ir­ish Times that, in gen­eral, obese pa­tients suf­fer from poor sleep for a va­ri­ety of rea­sons: “A big­ger size means a more cramped, un­com­fort­able bed; obe­sity is as­so­ci­ated with os­teoarthri­tis, and painful joints (hips, knees) dis­turb sleep; and a re­stricted night’s sleep causes hunger. Hunger, in turn, pro­motes overeat­ing, lead­ing to obe­sity. Late night feed­ing, par­tic­u­larly high-calo­rie food, causes fur­ther dis­rup­tion to sleep.”

Obe­sity, says Do­herty, leads to low self-es­teem which may de­velop into anx­i­ety or de­pres­sion. “In­abil­ity to fall asleep,” he ex­plains, “or re­cur­rent arousals from sleep, ie in­som­nia, are hall­mark find­ings of anx­i­ety or de­pres­sion. Un­for­tu­nately, anti-de­pres­sants or the med­i­ca­tions used to treat anx­i­ety can also af­fect nor­mal sleep ar­chi­tec­ture and worsen sleep pat­terns.”

The most im­por­tant med­i­cal cause of poor sleep in obese pa­tients is OSAS, says Do­herty, and its three char­ac­ter­is­tic symp­toms are heavy snor­ing, noc­turnal breath­ing ir­reg­u­lar­i­ties, and ex­ces­sive day­time sleepi­ness.

“The heav­ier you are,” he says, “the more likely you are to have OSAS. In my pa­per Bari­atric Surgery and its pos­i­tive im­pact on sleep, pub­lished in the Ir­ish Med­i­cal Jour­nal, we re­ported that not only did weight-loss suc­cess­fully treat OSAS, but it also im­proved day­time alert­ness in pa­tients with­out OSAS. It ap­pears that obe­sity dis­turbs sleep, and weight-loss im­proves sleep qual­ity.”

An­der­son of­fers fur­ther thoughts on sleep: “Tele­phones and gad­gets such as fit­bits are for days, not nights; if you wake re­freshed, you’ve had enough sleep; ex­er­cise is good for brains and bod­ies, and reg­u­lar light ex­er­cise as part of a day­time or early evening rou­tine, un­der­taken more than three hours be­fore bed­time is help­ful; and al­though we sleep a lit­tle less as we age, pro­tect­ing our time in bed is im­por­tant for long-term health.”

As Thomas Dekker wrote in The Guls Horne Book (1609): “Sleep is that golden chain that ties health and our bod­ies to­gether.”

Sleep is an au­to­matic ac­tion, like breath­ing, and in­som­nia comes from pay­ing too much at­ten­tion to some­thing we shouldn’t have to think about


The to­tal amount of sleep we re­quire changes as we age, with the av­er­age adult over 45 years need­ing about seven rather than eight hours of sleep.

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