Sleep Hygiene & Zeitgebers – High-Yield Notes

Sleep Hygiene

• Defined as daily habits & environmental adjustments that promote quality sleep and daytime alertness.

• Aim: fall asleep easily, stay asleep, wake refreshed.

Impact on Mental Wellbeing

• Poor sleep ⟷ mental illness (bidirectional relationship).

• Improving sleep hygiene can support psychological health.

Core Sleep-Hygiene Practices

• Consistent bed & wake times (even on weekends).

• Reserve bed only for sleep; avoid work, study, streaming.

• Keep bedroom dark, quiet, cool, comfortable.

• Limit screens/blue-light exposure ≥ 30 min before sleep.

• Avoid caffeine within 10 h, heavy meals within 3 h, vigorous exercise right before bed.

Zeitgebers ("time givers")

• External cues that align the circadian rhythm.

• Key zeitgebers: light, temperature, eating & drinking patterns.

Light

• Natural daylight = strongest zeitgeber; signals the SCN to promote wakefulness.

• Blue light (phones, laptops) mimics daylight → delays melatonin → later sleep onset.
  • Reduce blue-light exposure in evening (night-mode, blue-light filters, device curfew).

Temperature

• Body temperature naturally drops during sleep; a cool room assists this.

• Optimal bedroom temperature ≈ 18.3^\circ\text{C} (range 17^\circ\text{C} - 19^\circ\text{C}).

Eating & Drinking

• Caffeine = stimulant; avoid within 10 h of bedtime.

• Alcohol = depressant; may hasten sleep onset but fragments later sleep.

• Spicy, high-fat/sugar foods raise body temp & reduce sleep quality.

• Large meals near bedtime strain digestion; light snack is preferable.

Rapid Self-Check (Yes/No)

• Phone/laptop in bed?

• Bed used for non-sleep activities?

• Variable sleep/wake times?

• Caffeine after 15{:}00 if bedtime 23{:}00?

• Meals <3 h before bed?

• Exercise right before bed?

• Warm/hot bedroom?

Addressing more "Yes" answers → greater need to adjust habits.