Chelsea extended their winless run in the top flight to four matches with a 1-1 draw at the AMEX stadium.
Hakim Ziyech’s first half strike was cancelled out by Adam Webster’s free header in the second half.
Chelsea remain in third position on the table and are now 12 points behind leaders Manchester City, having also played a game more than the champions.
Chelsea’s trip to Brighton was their 15th game in all competitions since the start of December and Tuchel has acknowledged that tiredness has taken a toll on his team.
Asked to explain the recent poor league form, Tuchel replied: "I answered this question a hundred times, if you look at our situation of long-term injuries, of key players injured, and of Covid and you look at our schedule you will have the answer.
"We are mentally tired and physically tired, you can see it in our performance, it's as easy as that. We need to recharge the batteries, we need to reconnect.
"This is my feeling, that's why I give the players two days off and then we will use Friday and Saturday to prepare for Sunday."
When later asked how much his team needed two days off, he added: "So, so badly. You can say it's an excuse but it's like this.
"Look at our schedule when we arrived at Man City, we had Carabao Cup in between, they did not. When we arrived here, they had more days to prepare. We've played like this since November, we are the team that plays and plays and plays."
Chelsea return to action against Tottenham Hotspurs at Stamford Bridge on Sunday.
