Unit morale, fatigue and cohesion increase more rapidly during night and in some poor weather operations. While a unit may not necessarily lose its way, increases in the negative health measures will result in a range of failures from serious delay to abandonment of the order and routing to a rally point to recover.
It may be like that in the game, but in wartime procedures and results could be different.
During the German onslaught in France in 1940, the German inf units (non-motorized) following the motorized units had to perform forced marches and follow the path of the spearheading motorized units. To do so, they marched 4 hours, halted and rested (slept) on the roadside for 4 hrs and then marched another 4 hrs. Quite often, they would rest another few hours and then march again until midnight, in some instance even past midnight, if the last rest was a "full" 4-hrs period.
Veterans reported that the regime was kept for 3 or 4 days, straight. Many foot units kept up this regime for a few days until they had reached their interim goals or until the troops were totally exhausted. They would then rest for a half day or even a full day, before picking up the described cycle for another 1 or 2 days.
Veterans reported that they went through 2 or 3 pairs of boots during these forced marches in France.
A rather brutal (and pretty desperate) regime (dictated by the Russians) was maintained when the Germans had to retreat during the massive Russian offensive in the South in 1943, when the bulk of the German inf units had to retreat (I'd call it "run") from Taganrog via Mariupol, Perekop to Kherson (near the Dnjepr), if they didn't get a chance to evac by train from Mariupol or Stalino (both railroad hubs), via Nikopol (station), Zaorozhye (hub) to Krivoi Rog (station) or Kershon (=Cherson, hub).
Troops in non-motorized units had to cover the whole distance of 500 km along the coast (Taganrog - Kherson) on foot, where in theory either the slowest unit or the unit with the best equipment or health had to perform rearguard duties, but where quite often the Russians chased so hard, that the rearguards started to run themselves, resulting in constant fighting withdrawals, almost all along the retreat. In some areas the Russians halted after 300 km, but only because they had run out of fuel or ammunition, and because the supply units had to link up again, then they started to push again.
Quite often, the Germans would perform fighting withdrawals during the day and use lulls at night to steal away and to get some distance.
If I am not mistaken, this ordeal took weeks and months, until the Germans could establish temporary defensive lines (which were overrun eventually) and collection points, until they managed to establish a defensive line at the Dnjepr in December.
The detailed Veteran account I read about the retreat along or near the coastline described that the retreat involved weeks of marching, rerouting (which made it a trip of like 600 km for some units) and the constant danger of encirclement in the areas further north. I might dig out the report some time, it was pretty chilling, as it also emphasized that weak soldiers who weren't able to perform the marches and who didn't want to end up in Russian captivity were given Pervetin.
In the Pacific, Japanese units started their attacks when the sun came up, at first, but then increasingly resorted to (or added) night attacks, in areas with accurate Allied artillery fire. Pre-arranged Allied bombardments still kicked in, though, sometimes even just from single guns (eg. Autralian single arty at the Kokoda trail, or US arty on Guadalcanal or other islands), or fully fledged mortar units. US inf units would then rest during the day and prepare for helluva battle at night, for instance.
I think (and hope) that the fatigue regime and rules in the game have been changed, as a unit that had been ordered to rest/idle during the day, should be able to perform combat or march at night.
In confined areas, on fixed fronts, or during the first 48 hrs of an offensive, quite some units (Axis and Allies) had only 1 hr of sleep here and 2 hrs of sleep there, or they had to sleep in short shifts (eg. 4 hrs) or during lulls, before they could go back to a somewhat more humane regime again. I am not sure whether the engine considers such historical regimes, or not.
The Bundeswehr's Guard Bn securing the site of the old German Ministry of Defense still had a 24-hrs shift regime going in the late 80s/early 90s: 4 hrs patroling/guard post and 4 hrs of sleep for 24 hrs, and that was a (albeit special) peacetime shift. Just saying.