Sleep patterns in children and adolescents



Four age-related changes have been consistently demonstrated in polysomnographic (PSG) studies of sleep architecture:
- total sleep time (7-29),
- sleep efficiency (7,9-14,17-23,25-29,30-36), and
- slow wave sleep (7,8,10, 12-18, 21-28, 31,33, 35,37-39) all decrease, while
- wake after sleep onset (12-14,16,17,19,21,23,28,29, 32,33,36,37,40) increases with age.

Why such discrepancies between the studies?
Several factors may be responsible for the difficulties identifying age trends in sleep architecture of apparently healthy subjects. For example: small sample sizes; inconsistency in controlling factors that may influence sleep, such as mental or physical illness; insufficient screening for sleep disorders.

METHODS

TARGETED STUDIES

  • Non-clinical studies
  • Participants aged 5 to 18 years
  • measures of sleep characteristics by "all night" polysomography (PSG)
  • or measures of sleep-wake patterns obtained by questionnaires.
  • data presented numerically
  • published between 1960 and 2003 in peer-reviewed journals.

VARIABLES ANALYZED

  • Sleep latency (SL)
  • Sleep efficiency (SE)
  • Total sleep time (TST)
  • Stage 1,
  • stage 2,
  • slow wave sleep (SWS),
  • REM
  • REM latency
  • Minutes awake after sleep onset (WASO)
  • Bedtime & rising time

QUESTIONNAIRES

  • Number of studies: 21
  • Number of subjects: 24,617
  • Age range: 5-18 years
  • Data examined:
    • Bedtime,
    • rising time and
    • sleep duration for weekdays and weekends.
  • Europe versus USA

BEDTIME

Bed time
Weekday: age; interaction. Weekend: age; country; interaction.

RISING TIME

Rising time
Weekday: age; country; interaction. Weekend: age; country.

NIGHTTIME SLEEP DURATION

Nighttime sleep duration
Weekday: age; country; interaction. Weekend: age; country; interaction.

POLYSOMNOGRAPHY OR ACTIGRAPHY

  • Number of studies = 18
  • Number of subjects = 1,186 ¬®Age range: 5-18 years
  • Variables examined: TST, SL, SE, WASO, REM, S1, S2, SWS

SIGNIFICANT CHANGES

  • TST
  • Percentage stage 2
  • Percentage SWS
  • Percentage REM

TOTAL SLEEP TIME

Total sleep time

PERCENTAGE OF STAGE 2

Percentage of stage 2

PERCENTAGE SWS

Percentage sws

PERCENTAGE REM

Percentage rem

Discussion

QUESTIONNAIRES

Age effects for weekdays and weekends

  • Bedtime,
  • rise time,
  • total sleep time

Country effects

  • Weekday rise time & TST,
  • weekend bedtime, rise time,
  • TST

Interaction effects

  • Weekday bedtime,
  • rise time,
  • TST
  • weekend bedtime & TST

European studies focused more on younger samples than did US studies.
Patterns across age were reasonably consistent.

Interactions likely reflect socio-cultural differences.

PSG

Significant age-related changes in:

  • TST,
  • Stage 2 Sleep,
  • SWS,
  • REM

Extremely large variability.
Methodology may contribute to differences.

Careful controls and protocols are needed.

CONCLUSION

Normative data can provide a framework for understanding changes with age across time.

Societal and cohort differences may emerge as well-controlled studies emerge.