AP PSYCHOLOGY

Detailed explanation-1: -Entrainment denotes a process of coordinating the internal circadian clock to external rhythmic time-cues (Zeitgeber), mainly light. It is facilitated by stronger Zeitgeber signals and smaller period differences between the internal clock and the external Zeitgeber.

Detailed explanation-2: -The phase of entrainment refers to the relative timing of any circadian event within the objective 24-hour day. When good sleep hygiene is insufficient, a person’s lack of synchronization to night and day can have health consequences.

Detailed explanation-3: -The first mechanism is referred to as entrainment of the endogenous biological clock, which circumscribes temporarily the activity of the subject into day or night. The second mechanism is defined as masking, and this refers to an alternative route which does not involve the activity of the pacemaker.

Detailed explanation-4: -Free-running rhythms are characterized by a consistent delay in the timing of the circadian cycle by as much as 60 to 70 minutes per day and can be detected by measurement at regular intervals of a marker rhythm, such as the daily rise in the plasma melatonin concentration.