英语翻译ll human beings possess a body clock.Along with other al

英语翻译
ll human beings possess a body clock.Along with other alerting（警报）systems,this governs the sleep/wake cycle and is therefore one of the main processes which govern sleep behaviour.Typically,the preferred sleep/wake cycle is delayed in adolescents,which leads to many students not feeling sleepy until much later in the evenings.This typical sleep pattern is usually referred to as the “night owl” schedule of sleep.