Study

caffeine disrupts sleep

Caffeine disrupts sleep even when taken 6 hours before bedtime

A study found that consuming 400 mg of caffeine (equivalent to approximately 3-4 cups of coffee, depending on size and type) even 6 hours before bedtime significantly disrupts sleep, reducing total sleep time by over an hour. Participants often underestimated these effects, with objective measures showing greater disruption than subjective reports. These findings support avoiding caffeine at least 6 hours before sleep.

circadian disruption

Night shifts disrupt sleep and raise the risk of illness and accidents

Shift work can disrupt circadian timing and shorten sleep, which is linked to fatigue, reduced alertness, and higher accident risk. Evidence also links night and rotating shift work to modestly higher cardiovascular risk, while cancer evidence is mixed and depends on exposure definitions.

Insufficient-sleep-in-adolescents

Teenagers who sleep too little think and feel worse

Adolescents who lack sufficient sleep experience cognitive deficits including reduced attention, impaired learning, and worse academic performance. Sleep deprivation also increases anger, irritability, and emotional regulation difficulties, and leads to dangerous behaviors like risky driving. Research shows 8-10 hours of sleep per night is optimal for adolescents.