www.psychologytoday.com have a very useful article on loneliness. The key points are show below and the full article is available at the link.

KEY POINTS

• Loneliness is associated with negative outcomes, including both physical health and mental health problems.
• A recent investigation, using over 135,000 participants, concludes that a sense of purpose in life is protective against loneliness.
• To reduce loneliness, seek your life’s purpose—the thing that energizes your life, makes it worthwhile, and gives it direction.

Please see the full article here