First of all, try to let go of the expectation that you'll be able to "fully-internalize" all of the talks. That may help because retaining all of it is just not possible; unless of course you happen to be Venerable Ananda from the scriptures. Ananda was an attendant of the Buddha who had a super-normal capacity to remember everything that the Buddha said, which was very fortunate for us, otherwise we wouldn't have many of the scriptures. Most (maybe all) of the scriptures that begin with, "Thus have I heard...", were passed on to us thanks to Ananda's super-normal memory. But, of course, you have to remember that Ananda spent many years with the Buddha, so perhaps he heard the same teaching over and over.
A lot of our assistants have been here for a long time and they have heard some teachings over and over. Therefore, the teachings have become more familiar to them, and they are able to put them into practice more because they have become much more familiar. They have heard them often. The same with ourselves, it's almost impossible to remember everything, and sometimes we are very wise and sometimes we forget to be wise. We may even know the teachings but don't put them into practice all the time. So, first of all, try to let go of this strong expectation of yourself that you'll be able to "fully-internalize" all of the talks.
Sometimes when we are practicing during retreat, something will stand out, something that we need more practice with, and we practice it. We then understand it experientially and that will help us to understand the other talks more. There's going to be a lot of information given during these retreats and also a lot of reflections, try not to let it overwhelm you. You don't have to perfect all of these teachings in this 10-day retreat; it's purpose is to give you some more methods, techniques, and tools that you can use in your life. You can later, hopefully, review them and continue to learn how to use these tools more. When you hear it straight away you won't be able to understand everything or put everything into practice, especially at the beginning of a retreat, and especially if you're jetlagged; so try to have compassion for yourself.
Maybe do what we talked about earlier, the D/D method. Reflect that a lot of people get sleepy, have sleepless nights; it's not permanent, it'll pass away little-by-little. Sleepiness is very common in the beginning of a retreat; it happens even for experienced meditators in intensive retreat; sleepiness can arise for them. We just try to do the best we can and we don't have to be perfect.
Sometimes you may have to do more body awareness. When you are listening to the talks, it may be helpful to open your eyes. Oftentimes there is sleepiness in the beginning, so we have to have much more body awareness. Before the talks, perhaps do walking meditation at a faster pace to get the energy going. When you have the opportunity to do standing, stand up, so that the sleepiness doesn't overwhelm you.
Sometimes, when you are listening to a talk and there's still a lot of sleepiness, we often suggest that you have a contact with the earth - I don't know whether you can see me - but you can place one hand down touching the ground. Putting a bit of pressure on that hand often helps to make the mind a little bit brighter, more focused on the body. And when we kind of lose our focus, and get limp in the body and in the mind, we can try to bring our awareness back to the body. Bringing our awareness back to the body helps us to keep a bit more awake.
Also, it may be helpful to get more rest during the break times. See if you can catch up on some rest just by lying down. Sometimes, even if we don't sleep, it can be very helpful. And it's also very helpful to try not to worry and think that it's going to be permanent. I certainly have had a few times when I've arrived in Germany to teach and found that I'm jetlagged, and I'm sleepy, and I don't sleep very well. If I allowed my mind to worry and think, "Oh, I'm not going to have enough energy to teach tomorrow night and dada-dada-da...", then I won't. I try to see the worry, the fear, whatever it is, and just try to note it. Also as I just lay there, I reflect on the times when I was able to do it before, this way I bring up a bit more confidence that it will pass away.
And you can do a little bit of Compassion/Lovingkindness to anybody else, who at that time, is not able to sleep for any particular period. Oftentimes people are amazed that they can do things after they have not been able to sleep well at night. But other times they project a limited idea of themselves into the future and then totally believe in that limited capacity. However, it's often amazing actually, that if you just take things more moment-to-moment the next day, it goes fairly smoothly; that it is possible. So try not to project a limited idea of yourself into the future. This helps you to let go of the worry and the fear, and try to have Compassion and Lovingkindness for yourself before you try to sleep. Oftentimes just by laying there and allowing your body to relax, the body will get its rest. And if you can try to check your mind so that it doesn't go into worry and fear, and use it as an opportunity to meditate, you may find that you can fall asleep.