The cause of sleep problems can be many, lack of exercise being one of them, consuming the wrong foods and drinks (or in too high amounts) in the evenings, etc, however, nowadays some new big potential factors have arisen:

1) Bright light in the evenings from TV screens, laptops, tablets, LED lights and cell phones could be a factor.
2) EMF, like e.g. magnetic fields from smartphones, etc, could be a factor.
3) Over-stimulation of the brain by our modern technology and lifestyle could be a factor.

Because it's hard to know which people and studies are correct and which ones are false these days,

(because of bad science, bias and corruption) it's better to try many things yourself to see if it is true. Below are some references that at least provide some more info than found on mainstream TV and provided by some doctors, because what they provide can sometimes be overwhelmingly lacking, misleading and frustrating.

Please realize that not everything said in internet videos is always true either, but because a thing or two isn't entirely correct doesn't mean you should reject everything someone said either. You just need to try out which methods work for you and not.

2013 Documentary: "Resonance: Beings of Frequency" by James Russell
https://youtu.be/YFR5EtO_zdM?t=4055

Prof. Denis Henshaw: Magnetic Fields - Health Effects & Mechanisms
https://youtu.be/HZNrUrSdUzo?t=399

Multiple sleep tips by Kim
https://youtu.be/tVg7-ZHDjTE

The Gupta program
https://www.youtube.com/@GuptaProgram/videos

Is your Pineal Gland calcified and not functioning well?-----------------------------------------------------------

Daisy Maskell: Insomnia and Me - BBC