insomnia COVID-19 4 anxiety 4 Medicine 3 depression 3 fatigue 3 mental health 3 older adults 3 physical activity 3 rehabilitation 3 sleep 3 stress 3 COVID-19 pandemic 2 SARS-CoV-2 2 balance 2 biomarkers 2 burnout 2 chronic pain 2 diagnosis 2 emergency 2 exercise 2 falls 2 frailty 2 gender 2 infectious disease 2 personality 2 posttraumatic stress disorder 2 postural control 2 prevalence 2 prevention 2