There is the spiritual aspect and the physical aspect, they both apply.
-If you are in very good physical health but have spiritual problems, or uncertainty, that can keep you awake.
-Also, you may feel very healthy spiritually, having good fellowship with God, but be suffering from poor physical health either by 'chance' or consequence of sin, which can keep you awake.
Or in the worst cases, both.
Without more information it's just a guess but the way you say it's getting worse over time would seem to suggest physical, as spiritually the process of sanctification, if one is truly saved, should cause us to be more at peace over time and not less... closer to God; not that I haven't spent nights awake lamenting the state of the world, the depths of sin (my own included) that God suffers to take place until the next dispensation, but that type of thing is more situational not necessarily and inescapable everyday thing, something we choose to do... like an emotional fellowship with God, Jesus Christ.
It could be something as simple as vitamin D, it's so important God designed us such that we get it right from our skin and sunlight, but seeing as people wear so much clothing and spend so much time indoor's or otherwise "protected" from the sun they just don't get it, it is also very hard to acquire by diet, you also absorb less in general as you age.
Seeing as how you are posting this in the depths of winter (unless you are southern hemisphere) that is another clue, perhaps you also live at a high latitude...
Many here have quite an interest in natural health and healing by providing the body, God's design, what it was designed to have to function properly.
Many here are also good at assisting with spiritual problems, but that would require it's own type of assessment.
Seeing as how it's fast approaching midnight for me, I better try to get some myself.
I pray you will sleep soundly.
Pro 3:13 Happy is the man that findeth wisdom, and the man that getteth understanding.
Pro 3:24 When thou liest down, thou shalt not be afraid: yea, thou shalt lie down, and thy sleep shall be sweet.
Ecc 5:12 The sleep of a labouring man is sweet, whether he eat little or much: but the abundance of the rich will not suffer him to sleep.
1Ti 5:17 Let the elders that rule well be counted worthy of double honour, especially they who labour in the word and doctrine.