Most of us don’t need science to tell us that sleep and emotion are closely linked. Spend a couple nights with interrupted sleep or talk to any parent of a newborn and the connection is quite clear.
The connection appears not just in everyday life. In certain physical and mental disorders sleep disturbance and emotion dysregulation are hallmark symptoms. Symptoms of one rare disorder, cataplexy, which often co-occurs with the sleep disorder, narcolepsy for example, include sudden muscle weakness when a person experiences strong emotion, such as anger or fear, or exhilaration.
Lack of adequate sleep also is commonly linked with emotional or psychological problems. Examples include depression and PTSD, while sleep disturbances combined with emotional reactivity are key dimensions of bipolar disorder.
And even when lack of sleep isn’t connected to rare disorders or affective psychological problems, it is linked to increased emotionality.