COVID-19 is notorious for its neuropsychiatric sequelae. Some patients present with anosmia and cognitive and attention deficits, also known as “brain-fog”. In COVID-19 survivors, psychiatric manifestations such as depression, fatigue, anxiety, and neurocognitive impairments, also known as the “post-acute COVID-19 syndrome” or “long COVID”, were reported in 35% of the patients after the infection. New-onset anxiety, depression, psychosis, seizures, and even suicidal behaviors are also reported. Inflammation was proposed to be the pathophysiology.

The 68 year-old married female who lived with her husband did not have psychiatric history before this year. She had covid-19 infection 3 months prior to her psychiatric hospitalization. Although she had recovered, she started to have depressed mood, disrupted sleep and anhedonia since then. She became easily anxious and could hardly feed her cats as usual. She was not able to make decisions. She no longer did house chores that she had been doing. Poor appetite led to a loss of body weight from 46 to 40kgs. She had blunted emotional response, and could not cry after her cat died. She went to clinic for help, BZD and antidepressants were given, but the condition persisted. One week prior to hospitalization, her speech became weak, murmuring and could not finish a long sentence. The physiological change can be observed using wearable device. After 3 weeks of treatment, her heat rate, activity and sleep improved. The progress was also recorded via wearable devices and clinical scales.

In our patient, the depression was associated with circadian rhythm disruption, suicidal ideations and psychomotor slowing. This may reveal some special features of post-COVID depression. In previous studies, antidepressants have proved to be effective in treating post-COVID-19 depression. Sigma receptors are one of the possible mechanisms. Besides, agomelatine, with its melatonergic activity of regulating circadian rhythm, is proposed to have the potential to inhibit the virus from entering CNS. The activity pattern and circadian rhythm change will be discussed.