You may not know what to do or where to go for help, leading to more frustration, fear, concern and additional tasks that you really don't have time for. You should be aware that depression comes in many forms. Some episodes occur suddenly for no apparent reason. Some are triggered by a stressful experience. Some people have one episode in a lifetime, others recurrent episodes.
Some people go up and down vacillating between manic and depressed periods.
And, a little known fact, depression often occurs after a serious illness or in conjunction with being overmedicated. They cannot monitor themselves. If you love or are concerned about them, it is up to you help. The holidays are the most difficult time for those with a tendency towards depression. If you know someone who tends to get blue at this time of year, keep an eye on them and lend a helping hand.