I have noticed that I tend to get lucid dreams quite easily if I simply go to bed fairly early in the evening, about 9-10 PM - and conversely, I almost never become lucid if I go to sleep after midnight, when I feel fairly tired.
And this doesn’t even have anything to do with the time I am actually able to sleep during the night, because my assumptions are based on the nights when I have had all the time in the world to sleep in the morning.
It just seems like a huge difference when I go to sleep at 9 o’clock and wake up at say 6 o’clock, compared to when I go to sleep long after midnight and wake up sometime around 11 AM or even later, even if I sleep the same amount of time.
I’ve noticed a similar trend for myself. While I honestly don’t know if going to bed early would increase the likelihood of becoming lucid, I have an idea as to why it may happen. Everyone’s body has a different time at which it starts to produce melatonin to help them fall asleep, so I would guess that you might be producing the melatonin earlier in the night than later; thus, if you go to bed around the time that your body produces melatonin, then you are more likely to become lucid. Again, I have no clue if this is actually true, but it seems that it may be the reason for this phenomenon.
If any of that is confusing or you simply want to know more, I can give you a link to an article about this and also a website that can help you determine when your body starts to produce melatonin.
Melatonin is probably the answer.
Melatonin prevents the body from going to REM state, thus causing a rebound of longer REM cycles at the end of the sleep cycle.
It’s possible that if you go to sleep after the peek of your melatonin production, you body goes into REM sleep earlier and thus has shorter REM cycles later in the morning thus you are unable to get lucid.
To prove this, there are 2 options:
- when you become lucid, is it early during the night or more close to when you wake up?
- Did you try going to sleep later, but taking melatonin supplement?
Please note that I am not recommending you to take any supplement including melatonin unless you know what you are doing. Taking various nutritional supplements may be bad for you for various reasons. (allergy, wrong mix of supplements, poor manufacturing quality etc…)
I don’t think so… because i found that many people are sleeping late in the night still they get lucid…
matthewebbert: You do understand that LD is very unique per individual.
That’s one of the main reasons why it’s so hard to teach and practice.
The melatonin production process is something that stabilizes through maturity and is affected by environmental influences (light - dark cycle for example)
So the fact some people are going to sleep late (assuming by ‘late’ you mean something similar to the op’s definition), and have LD, doesn’t mean ‘time of going to sleep’ isn’t affecting the LD experience.
For example, it may very well be that if those people you talk about go to sleep early, they won’t have an LD either.
I’ve never told this to anyone because everyone should discover things by themselves but seeing that you are heavily struggling let me tell you the technique I use that has gotten me lucid the most including yesterday and the day after that and the day after that.
Take melatonin to boost dream bizarrenes and also REM. During the day keep your eyes and head centered straight(find out by yourself why it works its really good) and when you go to bed repeat the following mantra emotionless "I will ask myself in my dreams(at this point visualize a recent dream and you asking) am I dreaming?
Everyone is different but this is very solid if I knew you in person I would get in detail as to how you should think when repeating the mantra because I struggle putting it into words.
Melatonin does not hinder LD, to me it gives me a boost but don’t be one of those ignorants trying to ld by buying all the teas and pills without having basic knowledge, good luck.
Thank you, everyone. 
There was one more thing I would like ask about:
how do you think great changes in daylight affects your sleep cycles and your chances for becoming lucid?
I happen to live on a rather high latitude (central Sweden) and so the daylight around here varies quite dramatically - the summers are actually really bright, it can be daylight until around 11 PM and then sunrise as early as 3 AM;
and in winter it’s almost always dark instead.
Can this be a disadvantage?