It's possible to be completely isolated and feel invigorated.

• Scientific literature has linked loneliness to depression, anxiety, alcoholism, and drug abuse.
• Loneliness makes you more likely to fall ill by suppressing healthy immune function.
• Biochemical changes from loneliness an accelerate cancer, heart disease, and Alzheimer's.

• Research showed that after social isolation, subjects' brain scans showed more activity in the midbrain when shown pictures of social cues.
• When subjects were hungry but had not been socially isolated, they showed a similar reaction to food cues, but not social ones. This shows th...