You will be presented with the full text of a biomedical research paper. Please write an abstract for this paper. Your response should include the abstract and no additional text.

Paper text:
in terms of symptoms , women are less likely to report snoring or witnessed apnoea but are more likely to complain of daytime fatigue , lack of energy , insomnia , morning headaches , mood disturbance and nightmares compared to men [ 7 , 8 ] . in sleep studies , compared to men , women have a lower apnoea  hypopnoea index ( ahi ) , and their apnoeic episodes are shorter and less often associated with complete upper airway collapse .
women have less supine osa but clustering of apnoea during rapid eye movement ( rem ) sleep is common .
lower ahi in women is contrasted with higher occurrence of prolonged episodes of partial upper airway obstruction [ 36 ] , which typically appear in slow - wave sleep and are associated with increased carbon dioxide levels [ 9 , 10 ] .
increased carbon dioxide during sleep could be one possible reason [ 9 , 10 ] why women are symptomatic at relatively low ahi   and have a different symptom profile .
this is supported by the finding that in women , excessive daytime sleepiness and daytime fatigue are associated with habitual snoring , independent of ahi , age , obesity , smoking or sleep parameters .
partial obstruction is related to increased respiratory resistance , which is characterised by an increase in end - tidal   and transcutaneous carbon dioxide . correcting prolonged flow limitation with continuous positive airway pressure
( cpap ) treatment is associated with a higher attentiveness and a higher efficiency in normalising daytime vigilance than when eliminating only apnoea , hypopnea and snoring .
furthermore , hypercapnia is associated with electroencephalography ( eeg ) slowing and daytime sleepiness in sdb , and cpap treatment corrects the eeg slowing together with decreased daytime sleepiness .
both progesterone   and oestrogen   enhance genioglossus contractility , counteracting the upper airway collapsibility during sleep .
the increased respiratory drive caused by female hormones , particularly progesterone , may protect upper airway patency by enhancing upper airway dilator muscle activity .
conversely , the increased ventilatory drive associated with increased levels of progesterone [ 18 , 22 ] might cause a vacuum effect and increase the risk of upper airway collapsibility . by increasing respiratory drive and decreasing arterial carbon dioxide tension
carbon dioxide sensitivity is higher and upper airway resistance lower during the luteal phase ( high progesterone levels ) compared to the follicular phase [ 24 , 25 ] .
since the hypocapnic apnoeic threshold is higher in men than women , this suggests that the increased breathing instability during sleep in men is related to the presence of testosterone .
pregnancy , polycystic ovary syndrome and menopause are female - specific and sex hormone - dependent conditions that may predispose to sdb .
progesterone and oestrogen levels increase during pregnancy and decline during menopausal transition , whereas polycystic ovary syndrome is associated with androgen excess .
prevalence of snoring in pregnant women ranges from 10% to 45% and up to 75% in pre - eclampsia .
lean women are well protected from osa even in cases of multiple pregnancy , whereas in obese women , the prevalence is estimated to increase up to 10% by the first and 27% by the third trimester . increased minute ventilation , preference for
the lateral sleeping position in late gestation and decrease in rem sleep may protect against osa , whereas gestational weight gain , oedematous nasal mucosa , decreased lung functional residual capacity ( frc ) and increased arousals increase the osa risk .
the enlarged uterus causes diaphragmatic elevation leading to increased end - expiratory abdominal pressure , and reduced expiratory reserve volume and frc , which may result in less caudal traction of the trachea and pharynx , predisposing to increased airway collapsibility .
furthermore , the increased ventilatory drive associated with increased levels of progesterone   may cause a vacuum effect and increase the risk of upper airway collapsibility .
an obvious concern is that intermittent hypoxia could predispose to placental ischaemia and fetal growth retardation [ 30 , 31 ] . in an animal model ,
gestational chronic intermittent hypoxia resulted in intrauterine growth restriction and increased the risk of the offspring for metabolic diseases in adulthood .
especially in obese women , osa may be associated with increased risk of gestational diabetes , pregnancy - induced hypertension , pre - eclampsia , intrauterine growth retardation , preterm delivery , caesarean section and neonatal intensive care [ 30 , 31 ] .
conversely , pre - eclampsia might predispose to osa through fluid retention , rostral fluid shift and upper airway oedema .
potential shared pathophysiological mechanisms include oxidative stress , increased sympathetic activity , inflammation , adipokine effects and insulin resistance [ 30 , 31 ] .
sdb in women with pre - eclampsia typically manifests as flow limitation with increases in nocturnal carbon dioxide levels but with low ahi despite increased frequency of oxygen desaturations , particularly during rem sleep .
blood pressure responses to episodes of obstructive apnoea are augmented in normal pregnancy and further in pre - eclampsia .
the increased sympathetic activity during the third trimester contributes to the increased prevalence of osa , which in turn probably further augments sympathetic tone predisposing to pre - eclampsia .
cpap treatment reduces sleep - induced blood pressure increments and upper airway collapsibility   and improves fetal movement activity   in pre - eclampsia .
the prevalence of sdb in females doubles after menopause [ 3436 ] independently of age and bmi , the peak being at the age of 65 , 10  years later than in men .
less hyperpnoea after episodic hypoxia and more stable respiratory effort in non - rem sleep in response to hypercapnia and arousals might protect premenopausal females from osa . during menopausal transition , respiratory drive decreases .
increased arousals predispose to respiratory instability and increased soft tissue collapsibility aggravates upper airway obstruction .
however , obesity may have a sex - specific impact on prevalence and type of osa . in a study of more than 20  000 patients ,
osa severity increased linearly with age in normal - weight and obese women and in normal - weight men , whereas in obese men , ahi increased from age 20 to 40  years and remained stable thereafter . in 233 age- and bmi - matched male  female pairs , osa increased with increasing bmi only in men , whereas partial obstruction increased with moderate to morbid obesity in both sexes after the age of 65  years .
most studies have included only men and the few studies in females have had inconsistent results .
some studies have suggested higher [ 8 , 41 ] , some similar   and some even lower cardiovascular risk [ 43 , 44 ] in women with sdb compared to men .
lower risk of hypertension has been suggested in postmenopausal women with mild sdb ( snoring or ahi < 15 per h ) and using hormone therapy   or in those presenting with predominantly partial upper airway obstruction .
females with untreated osa , followed for 6.8  years , had a greater incidence of stroke and chronic heart disease than women without osa .
women seem to have a greater impairment in quality of life and higher healthcare expenditure than men with similar ahi severity .
women with osa had a two - fold increased risk of lost work days due to work disability compared to controls .
furthermore , the excess risk in women was already pronounced 5  years prior to the year of osa diagnosis , whereas in men , the highest risk was noticed 1  year before the year of diagnosis .
conventionally , the diagnosis of sdb is based on ahi , with an ahi > 5 per h being considered significant for diagnosis .
a higher ahi is sometimes required for initiation of nasal cpap therapy and an ahi > 30 per h is considered severe sdb , associated with marked comorbidity and decreased quality of life . in women ,  mild osa  may translate into as severe health consequences as osa with higher ahi in men [ 46 , 52 ] . considering increased fatigue in women with osa despite low / normal ahi , it has been suggested that symptomatic women with snoring or partial upper airway obstruction should be considered for treatment even if ahi < 5 per h [ 5 , 12 ] .
irrespective of sex , weight loss is the corner stone of treatment of sdb in obese patients . in women , weight loss may , however , be less efficient in decreasing osa severity . oral appliances may work better in women than in men .
, it is important to titrate the pressure to control not only osa but also episodes of partial upper airway obstruction [ 15 , 16 ] .
recent female - specific autotitrating algorithms for cpap devices may reduce flow limitation more efficiently but whether this results in better treatment outcome remains to be shown .
however , it is reasonable to apply similar , if not less stringent , criteria for treatment .
autoadjusting cpap devices are a feasible option responding to required pressure adjustments during pregnancy and post partum .
oral appliances may be impractical during pregnancy , since they may need multiple fitting sessions .
weight reduction or surgical procedures should be avoided until their safety in pregnant women is well - enough established .
menopause is associated with depletion of female sex hormones with concomitantly increased osa risk [ 34 , 35 ] .
hormone therapy might increase genioglossal activity   and apnoea threshold resulting in decreased propensity to periodic breathing and osa .
however , small interventional studies using different formulas of hormone therapy have provided conflicting results in alleviating sdb severity [ 18 , 57 , 58 ] . the inconsistent evidence and risks of hormone therapy do not justify its use to prevent or treat osa .
larger epidemiological studies of osa prevalence and fetal outcome during normal pregnancy and pre - eclampsia are needed .
this is due to the high prevalence of partial upper airway obstruction , resulting in clinically significant carbon dioxide increases during sleep . in symptomatic women with low ahi but marked partial upper airway obstruction , a cpap trial is often justified .
better understanding of the mechanisms through which different hormonal environments during a woman 's life span predispose to or promote progression of osa will ultimately lead to novel therapeutic options to prevent and treat sdb in women across all ages .
obstructive sleep apnoea ( osa ) is no longer considered to be a disease of males only . 
 the latest prevalence estimates of moderate - to - severe osa in women range from 6% to 20% [ 1 , 2 ] , resulting in male / female ratio from 3/1 to 2/1 [ 1 ] . 
 these figures may still underestimate the prevalence of sleep disordered breathing ( sdb ) in women , in whom the upper airway obstruction often manifests as noncountable , nonapnoeic respiratory events ( snoring , flow limitation or partial upper airway obstruction ) [ 36 ] . failure to recognise the distinct clinical presentation and partial obstruction in sleep studies may lead to under - recognition of sdb in females [ 7 , 8 ] . 
 for instance , prior to diagnosing osa , women are twice as likely as men to be treated for depression [ 7 ] .