This is why you feel MORE tired during the holidays, despite sleeping more than usual, according to an expert

Millions of Americans will enjoy the luxury of a few extra hours of sleep over the Christmas holiday weekend, but may not realize that they will likely pay the price later.

Sleeping longer than the recommended seven or eight hours each night, while this may seem like the best choice for recovering from a busy work week or the frenzy of preparing for the holidays, actually causes more dizziness and low energy during the day.

Each sleep cycle restarts every 80 to 100 minutes, so adding an hour or more to a night’s sleep usually means waking up in the middle of a deep sleep cycle, resulting in a post-hibernation hangover.

There are four sleep cycles, but waking up during the third, when sleep is deepest, will have the biggest impact on how a person feels during the day. After the third cycle comes REM, or the rapid eye movement cycle, in which we dream.

The brain goes through two different types of sleep: REM and non-REM, which include the early stage, when a person is just beginning to fall asleep, followed by light sleep, during which heart rate and breathing are regulated and body temperature drops.

The third stage is deep sleep, during which the brain can consolidate new memories and store them for the long term.

This phase is characterized by slow electrical waves that appear on a monitor as unevenly extended rolling hills, as opposed to the densely packed peaks and valleys that represent brain waves during wakefulness.

In REM, or rapid eye movement sleep, the electrical activity resembles that of an awake brain. During REM sleep, the brain continues to consolidate those memories and store them in long-term memory. It is also the stage where most dreams occur.

Doctors can detect when a person is in REM by examining facial twitches, eye movements behind the eyelids, and jaw tension.

The first cycle of REM sleep is short-circuited, about 10 minutes. But each cycle lengthens as more time is spent sleeping.

A person’s brain typically resets the cycle four or five times a night. Cycles typically last an average of 90 minutes, making optimal sleep duration around seven and a half hours.

Dr. Alexandria Reynolds, a sleep researcher and psychologist at the University of South Carolina, said: ‘If you woke up while you were in a deep sleep, you would wake up feeling super dizzy and super confused, and whoever woke you up might not be safe.

“If you wake up while you’re in REM sleep, you’ll feel much more rested, ready to tackle the day, and you’ll feel pretty good.”

This is because during REM sleep the brain is very active. Therefore, vivid dreams occur during the REM phase, making the transition to wakefulness smoother.

Dr. Reynolds added that on those mornings when someone wakes up on their own an hour before the alarm goes off, they should think twice before turning over for that extra hour of sleep, and instead get up and start the day .

‘You go back to sleep, you roll over, your alarm wakes you up and then you feel like crap… You should have gotten up. You overslept when your alarm woke you up,” she said.

But getting the recommended number of hours every night is easier said than done, and normal life can get in the way, whether it’s a heavy workload or a mad rush to get ready for the Christmas festivities.

The freedom of work-free weekends often leads people to think that napping longer on Friday and Saturday evenings will compensate for their sleep deprivation during the week. But experts argue that this is simply not how sleep works.

The more a person doesn’t get enough sleep over time, the more they build up sleep debt, and the harder it is to pay it off.

They’ve long said that you can’t compensate for lost sleep by napping more on your day off. When someone sleeps an extra hour or more on Saturday or Sunday morning, they typically have trouble falling asleep on schedule Sunday night, perpetuating the sleep debt cycle.

Dr. Jeffrey Iliff, a sleep and traumatic brain injury researcher at the University of Washington, said: ‘The sleep you lose is gone forever and a lot of the benefits of that sleep – which is memory consolidation or rejuvenation that happens in the brain – you kind of miss out on.’

Research has shown that this can take time up to four days of enough sleep to recover from just one hour of lost sleep and up to nine days of quality sleep to completely wipe out sleep debt.

A 2003 study conducted at the Walter Reed Army Institute of Research put the weekend nap catch-up method to the test.

In the study, 66 people spent three, five, seven or nine hours every night for a week, followed by three days of eight hours of sleep.

During the week, each participant underwent motor reaction speed and attention tests. During the three-day recovery phase, after several nights of longer sleep, those who rested for seven and five hours continued to perform as poorly on the tests as they did during the poor sleep week, with no significant improvement observed.

The three-hour sleep group saw their motor and attention skills improve after the first night of normal sleep, but their performance was not fully restored to normal and remained similar to that of the seven- and five-hour groups.

Getting too much sleep, just like too little sleep, can cause a litany of health problems, from headaches and low productivity to an increased risk of chronic heart disease, diabetes and obesity.

Sleeping for more than eight hours per night has also been linked to several mental health problems, including anxiety and depression. About 15 percent of people with depression sleep too much.

While sleeping too much can lead to negative health outcomes, it can also be indicative of an underlying condition, including sleep apnea that causes poor sleep quality throughout the night or hypersomnia, a condition in which people have excessive daytime sleepiness.

But, Dr. Reynolds said, “We won’t know the direction of causality until we do more experimental studies.”

Experts recommend maintaining a sleep schedule with the goal of consistently napping for about the same length of time, without overindulging a few nights a week.

Napping is a good option, but there is such a thing as “good” napping and “bad” napping.

Dr. Iliff said, “If you wake up after a nap and feel like you’ve just been hit by a truck, it’s because you’ve started building up what’s called sleep inertia.

“Once you start sleeping, after you get past a certain point, your brain goes into the mode of thinking, ‘Oh, we’re doing this for the next eight hours.’ and if you cut it off after it’s passed that point, it’s kind of a rude awakening.”

Experts recommend taking a short nap, about 25 minutes, or a longer nap of 90 minutes, which is enough time for the brain to go through an entire sleep cycle.