During slow or deep sleep parasympathetic activation is dominant, with decreased sweating and loss of psychogalvanic responses. Decreased mean heart rate, blood pressure and cardiac output are observed as well. The core temperature decreases slightly, but the thermoregulatory mechanisms work similarly to wakefulness. The cerebral oxygen consumption decreases. Muscle tone is lower than in wakefulness, with tonic contraction of the orbicularis oculi muscle. Cognitive activity persists during this period, although dreams are easily forgotten. The dream content is more logical-type and focuses on everyday aspects, particularly in the first sleep cycles.