Sleep across the lifespan

Question 1

Amount of sleep and wakefulness across the lifespan

Answer 1

We spend a lot of time asleep especially in the early years of our life and then sleep becomes less and less as we age. Sleep more in infancy than adulthood.

Question 2

Changes in Circadian Rhythm and Timing Across the Lifespan

Answer 2

Start off and finish off as morning people

In infancy we are early people and then in adolescence our clock is becoming more delayed and then we swing back in later life to early people again.

Question 3

Early entrainment

Answer 3

*Temperature
*Feeding

Mother
- melatonin
- corticosterone
- metabolism
- activity eg. exercise

Fetus
- hormones
-metabolism
- sleep-wake cycles

Input babies get is through the mothers circadian rhythms and what she is doing/ exposed to (eg. hormones, temperature, food, melatonin release)

First zietgebers the baby gets its through the mother

Whatever mother is doing, the baby is doing so if mother is in sync with the environment it helps the baby → eases entraining

Question 4

Entrainment in Premature Infants Constant vs Regular lighting

Answer 4

• Premature infants (32 weeks gestational age) in regular light–dark schedules in the Neonatal Intensive Care Unit (NICU) enjoy greater and more rapid weight gain compared to those in constant bright-light or dim-light conditions and have shorter hospital stays
• Premature infants kept in regular light–dark conditions in the NICU also fed orally sooner and spent fewer days on ventilator assistance (28–32 weeks of gestation)
• Infants kept in regular light-dark conditions cry less and are more active in the daytime
• Regular light–dark schedules support the maturation of sleep–wake and melatonin rhythms earlier

Question 5

Early Sleep
- what does infant sleep criteria not fit
- how many hours per day do infants sleep?
- what happens during the 24 hour period?

Answer 5

• Infant sleep does not fit the polysomnographic criteria of other ages (NREM, REM sleep), thus, sleep researchers use a different nomenclature
• Sleep 16-18h of sleep each day, most of which is spent in Active Sleep (AS)
• Alternate between sleep and wakefulness throughout the 24h period – polyphasic sleep (sleep is not really consolidated at night)

Question 6

Difference between Quiet Sleep, Active Sleep and Indeterminate Sleep

Answer 6

Quiet Sleep:
Similar to SWS in adults with absence of body movements

Active Sleep:
Irregular brain waves, body movements and occasional vocalizations (similar to REM)

Indeterminate Sleep (IS):
Sleep between QS and AS

For infants active sleep is their equivalent of REM sleep (brain activity, twitches, rapid breathing) in adults. Infants spend a large amount of time in this stage and they develop during this time.

Question 6

Early sleep:
1- gradually begin to…
2- what is there?
3- at ~3 months, what happens?
4- by 12 months…

Answer 6

1- Gradually begin to spend more time awake during the day and more time asleep at night
2- Strong homeostatic drive for sleep → frequent naps throughout the day
3- At ~3 months infant sleep begins to consolidate and to resemble sleep in later life (AS begins to resemble REM sleep and QS begins to resemble more NREM sleep).
4- By 12m of age babies nap on average twice daily and as they get older they have shorter naps

Question 7

Measures of sleep in childhood?

Answer 7

Self-reports, actigraphy, parent and/or teacher reports

(actigraphy- watches on wrists or ankles which monitors sleep activity of children)

Question 8

Childhood:
- when does REM sleep drop to adult levels?
- consistency of sleep?
- what is still high in children?
- toddlers and preschoolers stages of sleep?
- attempts to enter REM sleep?
- awakenings?
- ability to wake children from NREM sleep?

Answer 8

• By about 2 years of age, REM sleep drops to adult levels
• Sleep is fairly consistent and wake typically occurs at the same time on both weekdays and weekends
• Homeostatic sleep pressure in children is still very high
• Toddlers and preschoolers move quickly into deep sleep (enter stage 3). They may skip stages and not come up to the surface for long, they spend a long time in SWS.
• Attempts to enter REM sleep are often unsuccessful and they seem to ‘skip’ the first REM episode and go back to NREMs, mainly SWS, and then have a REM sleep bout
• Gradually fewer awakenings
• It is difficult to wake children from NREM sleep (early part of the night vs early morning)

Question 9

Avon Longitudinal Study of Parents and Children

What did they do and findings?

Answer 9

• Followed up ~7 thousand children born in 1991-1992 until they were about 11 years old
• Girls slept ~5-10 mins more than boys because of later wake-up time
• Children in the ALSPAC slept about 1 hour less in infancy and childhood compared to another cohort of children studied in Zurich born in 1974 -1978 and 1978-1993 and slept half an hour more in later childhood.

Question 10

Sleep duration and number of awakenings across childhood based on the ALSPAC

Answer 10

Started off sleeping for the majority of their time when they were young. Then their sleep started to become less and less

Average shows that by about 11 years old they would sleep for 9h 49mins on average.

Most of the children were waking up when they were young but as they get older their sleep consolidates (sleep without waking as much)

Question 11

Recommended Sleep Duration for Children and Teens by the American Academy of Sleep Medicine (AASM)

Answer 11

Infants (4-12m): 12-16h
Children (1-2y): 11-14h
Children (3-5y): 10-13h
Children (6-12y): 9-12h
Adolescents (13-18y): 8-10h

Question 12

Gender differences in infancy:
- boys vs girls CNS development
- girls sleep patterns and timing
- boys on average…
- SIDs?

Answer 12

• Boys lag behind girls in CNS development - linked to sudden infant death syndrome (SIDS) which is more frequent in boys (1.5x)
• By 6 months, girls have more organized sleep patterns, which suggests earlier entrainment (also evidenced by the circadian pattern in core temperature)
• Boys on average:
  — have shorter sleep bouts (5-10min on average) and earlier awakenings than girls
  — spend less time in quiet sleep (more active sleepers), wake up more frequently, and have lower sleep efficiency
• SIDS: occurrences of death in infants, especially in boys. Believed to be because the boy is lagging in immature lungs and it is difficult for them to breath
• Important to have them lie on their backs- having this recommendation reduced the occurrence of SIDS

Question 13

Prevalence of insomnia by gender and age groups
Calhoun et al 2014

Answer 13

Insomnia in 700 children (5-12 year old) using PSG and parental reports

5-7 and 8-10 years: not much difference between boys and girls, boys slightly higher than girls

11-12: girls are experiencing more insomnia compared to boys. Hormones are starting to kick in around this time which is one explanation for this disparity between boys and girls.

Question 14

Sleep duration in Children and Mental Health:
Gruber et al 2012- what did they do and findings

Answer 14

• Randomised control trial with blind teacher ratings on Emotional Lability, Restless-Impulsive Behaviour and daytime sleepiness (Conners’ Global Index)
• Measured sleep in 34 children aged 7-11y for 5 days by actigraphy (Baseline) and then assigned them to either 1h more or 1h less time in bed for a week
• When sleep was extended (~27min per night) there was detectable improvement in emotional lability and restless-impulsive behaviour scores of children in school and a significant reduction in reported daytime sleepiness
• When sleep was restricted (~54min per night) there was detectable deterioration on these measures.

Question 15

Rest-Activity measures and depression in adolescent boys
Merikanto et al 2017 study and findings

Answer 15

• Small sample of depressed non-medicated adolescent boys and healthy controls
• Recorded rest-activity cycles for 25 days using actigraphy
• Found blunted circadian rhythms in the depressed group compared to controls
• Depressed boys had lower activity levels and lower circadian amplitudes compared to healthy controls (didn’t have that contrast)
• Their most active hours were the hours spent in school, whereas the non-depressed boys were also active in the evenings and during weekends (perhaps more hobbies or social events)

Question 16

Meta-analysis on sleep and its impact
Astill et al 2012 study and findings

Answer 16

• Involved analysis of data from ~36,000 healthy school-children 5-12 years old, in an effort to summarize data and reach some conclusions
• Sleep duration was positively correlated with cognitive performance:
  – evident in executive functioning (eg. working memory, decision making, concentration, planning)
  – in complex tasks involving several cognitive domains
  – It was also positively correlated with school performance
• Short sleep duration was associated with behavioural problems, both internalizing and externalizing

Question 17

Sleep duration and behavioural problems/ cognitive performance

Answer 17

There is an association between sleeping more and having better behavioural outcomes and cognitive performance

Question 18

Adolescence sexual differentiation

Answer 18

• Organizational effects - critical period during prenatal development (masculinization and defeminization of the brain). Early effects that set us up to become men and women.
• Activation of these substrates takes place during puberty resulting in changes in behaviour
• Changes in ovarian steroid secretion in women coincide with sleep complaints

Question 20

Sleep in puberty:
- how are adolescents able to delay sleep for longer (Carskadon et al 1997)

Answer 20

Homeostatic sleep pressure slows so that adolescents can delay sleep for longer (Carskadon et al 1997)

— The circadian phase becomes more delayed which leads to more wakefulness in the evenings and later bedtime, which can be an hour at the onset of puberty

Question 21

Sleep in Puberty
- what happens to SWS in adolescence? girls vs boys?
- what begins to arise at puberty?
- what do girls have?

Answer 21

• SWS begins to decline in adolescence, with the decline in girls occurring around 1.2 years earlier compared to boys.
• At puberty, sleep complaints begin to arise, with girls reporting more difficulties than boys
• Girls have longer sleep onset latency (they are in bed but they cannot go to sleep as quickly) and greater rates of insomnia (trouble going to sleep) **, which persist across the lifespan
• Insomnia symptoms are correlated with behavioural and mental health issues in boys and girls

Question 22

Sleep in Adolescents is Shrinking:
- National surveys in the US, report of people sleeping 8-9.5h per night
- sleep in childhood/ adolescence?
- what did ‘Monitoring the future’ survey in US 1991-2012 find?
- what is the trend of decline in adolescent sleep known as?

Answer 22

• National surveys in the US, only 7% sleep 8-9.5h per night
  – Between 12-18 years of age, the probability of getting at least 7h or sleep each night drops by about half (7 hours of sleep is 2h less than the recommended 9 hours of sleep)
• Sleep declines from childhood to adolescence but also there is a historical shift taking place
• ‘Monitoring the future’ survey in US 1991-2012 with more than 270,000 high-school students in the US, found a major decrease in sleep over the past few years, with the greatest shift observed in 15-year olds
• This worrisome trend of decline in adolescent sleep over the past 20 years is coined as the ‘great sleep recession’ (Keyes et al 2015, Journal Pediatrics)

Question 23

‘Great Sleep Recession’ - Keyes et al 2015

Answer 23

• % of adolescents that report equal or greater than 7 hours of sleep per night
• around 65% at age 12 sleep but then this declines especially around age 15. Then there is a further shift as they get closer to adulthood.
• There is a trend of things getting worse with adolescents with regular adequate sleep
• from 12 years get less and less sleep as we go through adolescent years

Question 24

Matricciani et al 2013

Answer 24

The National Sleep Foundation recommended children age 9-18y get 8.5-9.25h of sleep

The National Heart, Lung and Blood Institute recommends 10h of sleep

Harvard recommends 9 h of sleep

Question 25

‘Young people need experiences that boost their mental health’

Fuligni & Galvan

Answer 25

Getting less sleep is associated with worsening mental-health, such as increases in feelings of sadness and hopelessness
(Youth Risk Behavior Surveillance System)

% of people getting 7 hours of less is increasing over time

teenagers get less and less sleep and at the same time there is a corresponding increase in more mental health issues.

Increase in cancer rates in young people. Studies point out that decreased sleep might contribute to this.

Question 26

What may be the factors that keep adolescents up these days?

Answer 26

• Electronic screens and light exposure
• Social media (anxiety, other concerns)
• Homework
• Work/Study
• Caffeine
• Energy drinks
• Substance use

Question 27

Parental Role:
- what is sacred in the early years
- what do parents set?
- US study on bedtimes findings (childhood to adolesence)

Answer 27

• In the early years, bedtime routine is sacred.
• Bedtimes are usually set by parents in childhood but less so in adolescence (so they enforce sleep in children)
• US study found less than 1-in-5 have a parent-set bedtime at age 10 and this drops to less than 1-in-20 at age 13 (Carskadon, 1990)
• A shift in parental involvement from enforcing bedtime to becoming the alarm
• Greater difference between weekdays and weekends

Question 28

Use of digital devices and social media
1- impact on sleep?
2- % of devices found in the bedroom and % of use 1 hour before bedtime
3- Hale and Guan, 2015 finding
4- In what ways can digital use interfere with sleep

Answer 28

1- Pervasive use of screen-based media may be responsible for reduced sleep in children and adolescents (Le Bourgeois et al 2017-Pediatrics)

2- These devices are often (75%) found in the bedroom (this is a significant predictor of reduced bedtime) and 60% of adolescents report using the device 1h before bedtime

3- A systematic literature review between 1999-2014 on screen use and sleep found that screen use was negatively impacting sleep by delaying sleep time and thus reducing sleep (by Hale and Guan, 2015)

4- Digital use may interfere with sleep on multiple levers:
- delayed bedtime (time displacement)
- light exposure
- psychological stimulation

Question 29

Use of digital devices
1- findings of studies looking at digital use and sleep
2- what digital device interferes the most?
3- what did Mullan 2018 find?
4- Yang et al. (2019) finding?

Answer 29

1- Many studies around the world have found delayed sleep time due to digital use

2- Smart phones, computers etc are more interfering than TV watching

3- Mullan 2018 – children in the UK are spending 4.45 per day on electronic devices (8-18y olds) and indicated an increase in digital use in the last few years 2010-2015 as well as an increase in alone-together time (together as a family/ friend group but everyone is focused on a separate activity)

4- Around 52,000 participants in a US survey, found that computer use during leisure has increased from 2001-2016, a part of a sedentary lifestyle in both adults and adolescents (Yang, et al, 2019, JAMA)

(lack of exercise due to work is a negative effect of sedentary lifestyle. For young people in front of screens this is detrimental as they should be running around and using energy)

Question 30

SCREENS: A family and home-based randomized control trial on children 4-14 years of age

Answer 30

• Launched in Denmark and published in 2022 JAMA Pediatrics (Pedersen et al)
• In Denmark 88% of adults report using the internet daily whereas school children (24% of boys and 19% of girls) spend at least 4 hours per day using digital devices (Folkesundhed, 2019)
  – 45 families as experimental group and 44 families as control group
• Baseline data and then for 2 weeks they had no smartphones and only be allowed screen time 3 hours per week or less
• Found a substantial increase in children’s physical activity

Question 31

Early school start times:
- what did the NSF survey in 2006 find?
- US Air Force?

Answer 31

• NSF survey in 2006 found that 28% of high school students reported falling asleep in class at least once a week
• US Air Force – first semester freshmen randomly assigned to different schedules

– Those randomly assigned to take a class before 8am had significantly worse academic performance in their first hour class compared to those with the first hour assigned at or after 8am
– In addition, performance throughout the day was reduced

(no matter what time you go to bed, school starts at the same time, shrinkage in hours we have available to sleep)

Question 32

Later school start times
- what are they associated with?
- impact on health/ behaviour problems?

Answer 32

• Later school start times are consistently associated with fewer symptoms of depression and anxiety
• Improved general mental health and reduced psychologically relevant behaviour problems such as emotional problems and hyperactivity/inattention

Question 33

Sleep in adolescence sum

Answer 33

• There is a shift towards a delayed circadian phase during adolescence, but not a decrease in sleep need
• There is a major trend of reduced sleep in adolescents. Getting worse across time.
• Digital devices, social life and school-work interfere with their ability to sleep sufficiently

Question 34

Sleep in Adulthood: Key feature

Answer 34

Under-sleeping

• Common theme in young adulthood with environmental factors contributing to insufficient sleep
• Many adults do not get the recommended 7-9 hours of sleep
• Gradual reduction of sleep per decade of our lives with a tendency towards lighter sleep which plateaued at the age of 60 years
• Only about half of the adults get enough sleep

Question 35

Average sleep in adults
Data from the Behavioral Risk Factor Surveillance System (BRFSS)-USA (2014)

Answer 35

~36%: <(=) 3 hours to 6 hours
~56%: 7/8 hours
~8%: 9 hours to >(=) 11 hours

Question 36

Sex Differences in Sleep:
1- diff in sleep quality?
2- diff in total sleep time, total wake time, shorter sleep onset latency, sleep efficiency?
3- diff in lightness of sleep
4- SWS activity, sleep intensity?
5- subjective measures of sleep findings?

Answer 36

1- women have better PSG-defined sleep quality than men.
2- Women have significantly longer total sleep time and less total wake time, a shorter sleep onset latency and better sleep efficiency compared to men
3- Portable PSG measures also find that men have lighter sleep compared to women. Men also have more arousals and lower sleep efficiency
4- SWS activity, a measure of sleep intensity is greater in women across ages and greater in recovery sleep
5- However, in subjective measures of sleep, women report insufficient sleep and more sleep-associated disruptions compared to men paradox

Question 37

Sex diff and circadian rhythms:
1- diff in going to bed?
2- timings in other circadian rhythms such as temperature and melatonin
3- what are still not known
4- what is there an important sex difference for?

Answer 37

1- Women tend to go to bed earlier and wake up earlier compared to men – women are generally more morning people
2- On average, women have earlier timing in other circadian rhythm such as temperature and melatonin
3- Mechanisms are still not known
4- An important sex difference exists for insomnia, with women having 40% greater risk for insomnia compared to men

Question 38

Prevalence of insomnia complaints by sex and age

Answer 38

Generally, insomnia affects females more
Similar in early life but more differences as we move into adulthood

Question 39

Hormone levels and sleep across stages of reproductive age
Haufe and Leeners, 2023

Answer 39

Menstrual cycle:
changes in sleep behaviour- increased insomnia, increased deep sleep, decrease sleep quality
confounders- premenstrual syndrome, dysmenorrhea, mood disorders
hormone associated with sleep disruption- decreased progesterone (late luteal, premenstrual)

Pregnancy:
changes in sleep behaviour- increased restless legs syndrome, increased sleep-disordered breathing, decreased sleep duration, decreased sleep quality
confounders- pregnancy related factors (nocturnal micturition, reflux, muscoskeletal discomfort), infants sleep/ wake rhythm postpartum, mood disorders
hormone associated with sleep disruption-

Menopause Transition:
changes in sleep behaviour- increased insomnia, increased sleep-disordered breathing, increased awakenings, decreased sleep duration, decreased sleep quality
confounders- vasomotor symptoms, age, stress hormones, mood disorders
hormone associated with sleep disruption- decreased estrogen, decreased progesterone

(hormones are beginning to fluctuate, hot flushes, changes in body, troubles with sleep)

Postmeopause:
changes in sleep behaviour- increased insomnia, increased sleep-disordered breathing, increased awakenings, decreased sleep duration, decreased sleep quality
confounders- vasomotor symptoms, age, stress hormones, mood disorders
hormone associated with sleep disruption- decreased estrogen, decreased progesterone

Question 40

Sex steroids and sleep - women

Answer 40

Sleep disturbances increase when there are fluctuations in ovarian hormones, as in puberty, menstrual cycle (Baker et al 2007), pregnancy and menopause (Moline et al 2004)

Question 41

Prevalence of sleep disturbance and daytime fatigue by age and sex

Answer 41

women are consistently recording more sleep disturbances

Question 42

Menopause:
1- characterised by?
2- accompanying symptoms include?
3- mostly what studies?
4- Lampio et al 2017

Answer 42

1- Characterised by fluctuations and eventual decline in oestrogens associated with sleep disruption, mainly sleep awakenings
2- Accompanying symptoms such as hot flushes affect the majority of women
3- Mostly cross-sectional studies
4- Lampio et al 2017 - the only longitudinal study of sleep and menopause at baseline and 6 years later with 60 women participants (47-52years of age)

Question 43

Hypnogram pre-menopause and 6 years later during peri-menopause (Lampio et al 2017)

Answer 43

When experiencing menopause, also experiencing several periods of wakefulness

Question 44

Sleep disturbances in older adults
- changes in?
- may be?
- other factors which can be stressful?

Answer 44

• Changes in medical conditions, medications, changes in social engagement and lifestyle, living environment etc
• May be more sedentary, less active and socially active which may impact sleep homeostasis and circadian regulation
• Life events such as loss of loved ones, moving into care homes, can be stressful

Question 45

Sleep in the Elderly

Answer 45

• Fraying sleep but major individual differences - According to the American National Sleep Foundation 44% of elderly adults complain about their sleep at least a few nights per week
• Changes begin in mid to late middle age but become intense and more noticeable in the elderly
• Sleep onset (going to sleep) becomes more difficult (longer sleep onset latency) and night-time awakenings more prevalent in the elderly
• Sleep at night may decrease but total sleep in the 24h period may not decrease if people nap
  – More opportunities to nap compared to other times in their life

Question 46

Sleep in Old Age
- what do measures of daytime sleepiness suggest?
- what happens to circadian rhythms?
- what do older adults report in surveys?
what do many older adults experience?

Answer 46

• Measures of daytime sleepiness suggest that the elderly are sleepier during the day than when they were younger
• Circadian rhythms advance, causing early evening sleepiness and early morning awakenings
• In surveys, older adults report less satisfying sleep compared to when they were younger
• For many older adults there is a reduction in the depth and quality of sleep, with decreased sleep duration and increased nocturnal awakenings (Dijk and Duffy, 1999)
  – more likely to be awoken by auditory stimuli which is in agreement with changes in sleep depth

Question 47

Deterioration of Rhythmicity in the Elderly

Answer 47

Becoming even earlier people than they were when they were adults

Aging changes functioning of molecular clock - SCN starts to drift off and deteriorate

Question 48

In vivo studies in rodents and the SCN:
- what happens to rhythmicity?
- what have transplantation studies shown?
- what happens with advancing age?
- what does emerging evidence suggest that sleep disruptions and complaints precede?
- RBD?

Answer 48

• Deterioration of rhythmicity as a result of a decline of the integrity of the SCN
• Transplantation studies have revealed that young SCN grafts lead to improvement of the activity rhythm & amplitude of aged mice suggesting that the age-related phenotype is caused primarily by deterioration in the function of the SCN (Hurd and Ralph, 1998)
• With advancing age melatonin production decreases which may also contribute to changes in sleep patterns
• Emerging evidence suggests that sleep disruptions and complaints precede the emergence of dementia and related disorders (Pase et al, 2017)
• RBD: REM behaviour disorder- people are acting out on their dreams
  for 80% of those that have RBD, they go on and develop parkinsons disorder