Sleep deprivation increases production of the stress hormone cortisol and decreases levels of leptin, which tells your brain if you've had enough to eat. (blog.fitplanapp.com)
The increased production of these stress hormones also affects all the cells in your body including the nails and hair. (healthnfitnesshops.com)
The sympathetic nervous system stimulates production of stress hormones, increasing blood pressure and heart rate and preparing us for the «flight or fight» response. (mindbodygreen.com)