Evidence that sleep is important is overwhelming. Elegant research has demonstrated its critical role in memory consolidation and our ability to generate innovative solutions to complex problems. Sleep disruption increases the level of the stress hormone cortisol. Impulsive behaviors, lack of empathy, sense of humor, and mood are similarly affected.
All in all, a tired adolescent is a grumpy, moody, insensitive, angry, and stressed one. Perhaps less obviously, sleep loss is associated with metabolic changes. Research has shown that blood-glucose regulation was greatly impaired in young men who slept only four hours on six consecutive nights, with their insulin levels comparable to the early stages of diabetes.
Similar studies have shown higher levels of the hormone ghrelin, which promotes hunger, and lower levels of leptin, which creates a sense of feeling full. The suggestion is that long-term sleep deprivation might be an important factor in predisposing people to conditions such as diabetes, obesity, and hypertension.
Adolescents are increasingly using stimulants to compensate for sleep loss, and caffeinated and/or sugary drinks are the usual choice. The half-life of caffeine is five to nine hours. So a caffeinated drink late in the day delays sleep at night. Tiredness also increases the likelihood of taking up smoking.
Collectively, a day of caffeine and nicotine consumption, the biological tendency for delayed sleep, and the increased alertness promoted by computer or cellphone use generates what Carskadon calls a perfect storm for delayed sleep in teenagers.
What a mess. Poor kids.