It's possible, if you're physically tired, then yes, we would recommend that you get a bit more rest. If you're really exhausted, from say missing a whole night of sleep, then write us a note, we often let people skip the first sit. Not a problem.
But the person writes "If the hindrance "sleepiness"...". Now, physical tiredness certainly will hinder you. If you're tired, ill, injured and such, then you actually have to do something to correct that problem. So if it's actually sleepiness coming from a lack of sleep, that's one thing and we recommend that you get more rest.
That's a whole different issue to what we normally call the hindrance "sleepiness", or as we say in the regular retreat, "Sloth and Torpor". What we normally call "Sloth and Torpor" is a manifestation that comes about often because we're bored, or we have some aversion, we don't want to look at something in the mind, and we get caught in sloth and torpor. We just feel it would be better to disappear for a while. So that hindrance is quite different to actually being physically tired. To know the difference between these two would be really helpful. If you are actually physically tired, go ahead have more sleep during the break times.